Adding the test "tst-safe-linking" for testing that Safe-Linking works
as expected. The test checks these 3 main flows:
* tcache protection
* fastbin protection
* malloc_consolidate() correctness
As there is a random chance of 1/16 that of the alignment will remain
correct, the test checks each flow up to 10 times, using different random
values for the pointer corruption. As a result, the chance for a false
failure of a given tested flow is 2**(-40), thus highly unlikely.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Alignment checks should be performed on the user's buffer and NOT
on the mchunkptr as was done before. This caused bugs in 32 bit
versions, because: 2*sizeof(t) != MALLOC_ALIGNMENT.
As the tcache works on users' buffers it uses the aligned_OK()
check, and the rest work on mchunkptr and therefore check using
misaligned_chunk().
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Removed unneeded '\' chars from end of lines and fixed some
indentation issues that were introduced in the original
Safe-Linking patch.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Safe-Linking is a security mechanism that protects single-linked
lists (such as the fastbin and tcache) from being tampered by attackers.
The mechanism makes use of randomness from ASLR (mmap_base), and when
combined with chunk alignment integrity checks, it protects the "next"
pointers from being hijacked by an attacker.
While Safe-Unlinking protects double-linked lists (such as the small
bins), there wasn't any similar protection for attacks against
single-linked lists. This solution protects against 3 common attacks:
* Partial pointer override: modifies the lower bytes (Little Endian)
* Full pointer override: hijacks the pointer to an attacker's location
* Unaligned chunks: pointing the list to an unaligned address
The design assumes an attacker doesn't know where the heap is located,
and uses the ASLR randomness to "sign" the single-linked pointers. We
mark the pointer as P and the location in which it is stored as L, and
the calculation will be:
* PROTECT(P) := (L >> PAGE_SHIFT) XOR (P)
* *L = PROTECT(P)
This way, the random bits from the address L (which start at the bit
in the PAGE_SHIFT position), will be merged with LSB of the stored
protected pointer. This protection layer prevents an attacker from
modifying the pointer into a controlled value.
An additional check that the chunks are MALLOC_ALIGNed adds an
important layer:
* Attackers can't point to illegal (unaligned) memory addresses
* Attackers must guess correctly the alignment bits
On standard 32 bit Linux machines, an attack will directly fail 7
out of 8 times, and on 64 bit machines it will fail 15 out of 16
times.
This proposed patch was benchmarked and it's effect on the overall
performance of the heap was negligible and couldn't be distinguished
from the default variance between tests on the vanilla version. A
similar protection was added to Chromium's version of TCMalloc
in 2012, and according to their documentation it had an overhead of
less than 2%.
Reviewed-by: DJ Delorie <dj@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Adhemerval Zacnella <adhemerval.zanella@linaro.org>
If the test fails due some unexpected failure after the children
creation, either in the signal handler by calling abort or in the main
loop; the created children might not be killed properly.
This patches fixes it by:
* Avoid aborting in the signal handler by setting a flag that
an error has occured and add a check in the main loop.
* Add a atexit handler to handle kill child processes.
Checked on x86_64-linux-gnu.
pvalloc is guarantueed to round up the allocation size to the page
size, so applications can assume that the memory region is larger
than the passed-in argument. The alloc_size attribute cannot express
that.
The test case is based on a suggestion from Jakub Jelinek.
This fixes commit 9bf8e29ca1 ("malloc:
make malloc fail with requests larger than PTRDIFF_MAX (BZ#23741)").
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This patch moves the vDSO setup from libc to loader code, just after
the vDSO link_map setup. For static case the initialization
is moved to _dl_non_dynamic_init instead.
Instead of using the mangled pointer, the vDSO data is set as
attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for
static). It is read-only even with partial relro.
It fixes BZ#24967 now that the vDSO pointer is setup earlier than
malloc interposition is called.
Also, vDSO calls should not be a problem for static dlopen as
indicated by BZ#20802. The vDSO pointer would be zero-initialized
and the syscall will be issued instead.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu,
powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and
sparcv9-linux-gnu. I also run some tests on mips.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
I've updated copyright dates in glibc for 2020. This is the patch for
the changes not generated by scripts/update-copyrights and subsequent
build / regeneration of generated files. As well as the usual annual
updates, mainly dates in --version output (minus libc.texinfo which
previously had to be handled manually but is now successfully updated
by update-copyrights), there is a fix to
sysdeps/unix/sysv/linux/powerpc/bits/termios-c_lflag.h where a typo in
the copyright notice meant it failed to be updated automatically.
Please remember to include 2020 in the dates for any new files added
in future (which means updating any existing uncommitted patches you
have that add new files to use the new copyright dates in them).
do_set_tcache_max, do_set_mxfast:
Fix two instances of comparing "size_t < 0"
Both cases have upper limit, so the "negative value" case
is already handled via overflow semantics.
do_set_tcache_max, do_set_tcache_count:
Fix return value on error. Note: currently not used.
mallopt:
pass return value of helper functions to user. Behavior should
only be actually changed for mxfast, where we restore the old
(pre-tunables) behavior.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
set_max_fast sets the "impossibly small" value based on,
eventually, MALLOC_ALIGNMENT. The comparisons for the smallest
chunk used is, eventually, MIN_CHUNK_SIZE. Note that i386
is the only platform where these are the same, so a smallest
chunk *would* be put in a no-fastbins fastbin.
This change calculates the "impossibly small" value
based on MIN_CHUNK_SIZE instead, so that we can know it will
always be impossibly small.
Fixes `<total type="rest" size="..."> incorrectly showing as 0 most
of the time.
The rest value being wrong is significant because to compute the
actual amount of memory handed out via malloc, the user must subtract
it from <system type="current" size="...">. That result being wrong
makes investigating memory fragmentation issues like
<https://bugzilla.redhat.com/show_bug.cgi?id=843478> close to
impossible.
memusagestat may indirectly link against libpthread. The built
libpthread should be used, but that is only possible if it has been
built before the malloc programs.
GCC mainline has recently added warn_unused_result attributes to some
malloc-like built-in functions, where glibc previously had them in its
headers only for __USE_FORTIFY_LEVEL > 0. This results in those
attributes being newly in effect for building the glibc testsuite, so
resulting in new warnings that break the build where tests
deliberately call such functions and ignore the result. Thus patch
duly adds calls to DIAG_* macros around those calls to disable the
warning.
Tested with build-many-glibcs.py for aarch64-linux-gnu.
* malloc/tst-calloc.c: Include <libc-diag.h>.
(null_test): Ignore -Wunused-result around calls to calloc.
* malloc/tst-mallocfork.c: Include <libc-diag.h>.
(do_test): Ignore -Wunused-result around call to malloc.
Change the tcache->counts[] entries to uint16_t - this removes
the limit set by char and allows a larger tcache. Remove a few
redundant asserts.
bench-malloc-thread with 4 threads is ~15% faster on Cortex-A72.
Reviewed-by: DJ Delorie <dj@redhat.com>
* malloc/malloc.c (MAX_TCACHE_COUNT): Increase to UINT16_MAX.
(tcache_put): Remove redundant assert.
(tcache_get): Remove redundant asserts.
(__libc_malloc): Check tcache count is not zero.
* manual/tunables.texi (glibc.malloc.tcache_count): Update maximum.
The tcache counts[] array is a char, which has a very small range and thus
may overflow. When setting tcache_count tunable, there is no overflow check.
However the tunable must not be larger than the maximum value of the tcache
counts[] array, otherwise it can overflow when filling the tcache.
[BZ #24531]
* malloc/malloc.c (MAX_TCACHE_COUNT): New define.
(do_set_tcache_count): Only update if count is small enough.
* manual/tunables.texi (glibc.malloc.tcache_count): Document max value.
This synchronization method has a lower overhead and makes
it more likely that the signal arrives during one of the critical
functions.
Also test for fork deadlocks explicitly.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
The memusagestat is the only binary that has its own link line which
causes it to be linked against the existing installed C library. It
has been this way since it was originally committed in 1999, but I
don't see any reason as to why. Since we want all the programs we
build locally to be against the new copy of glibc, change the build
to be like all other programs.
Remove do_set_mallopt_check prototype since it is unused.
* malloc/arena.c (do_set_mallopt_check): Removed.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: DJ Delorie <dj@redhat.com>
As discussed previously on libc-alpha [1], this patch follows up the idea
and add both the __attribute_alloc_size__ on malloc functions (malloc,
calloc, realloc, reallocarray, valloc, pvalloc, and memalign) and limit
maximum requested allocation size to up PTRDIFF_MAX (taking into
consideration internal padding and alignment).
This aligns glibc with gcc expected size defined by default warning
-Walloc-size-larger-than value which warns for allocation larger than
PTRDIFF_MAX. It also aligns with gcc expectation regarding libc and
expected size, such as described in PR#67999 [2] and previously discussed
ISO C11 issues [3] on libc-alpha.
From the RFC thread [4] and previous discussion, it seems that consensus
is only to limit such requested size for malloc functions, not the system
allocation one (mmap, sbrk, etc.).
The implementation changes checked_request2size to check for both overflow
and maximum object size up to PTRDIFF_MAX. No additional checks are done
on sysmalloc, so it can still issue mmap with values larger than
PTRDIFF_T depending on the requested size.
The __attribute_alloc_size__ is for functions that return a pointer only,
which means it cannot be applied to posix_memalign (see remarks in GCC
PR#87683 [5]). The runtimes checks to limit maximum requested allocation
size does applies to posix_memalign.
Checked on x86_64-linux-gnu and i686-linux-gnu.
[1] https://sourceware.org/ml/libc-alpha/2018-11/msg00223.html
[2] https://gcc.gnu.org/bugzilla//show_bug.cgi?id=67999
[3] https://sourceware.org/ml/libc-alpha/2011-12/msg00066.html
[4] https://sourceware.org/ml/libc-alpha/2018-11/msg00224.html
[5] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87683
[BZ #23741]
* malloc/hooks.c (malloc_check, realloc_check): Use
__builtin_add_overflow on overflow check and adapt to
checked_request2size change.
* malloc/malloc.c (__libc_malloc, __libc_realloc, _mid_memalign,
__libc_pvalloc, __libc_calloc, _int_memalign): Limit maximum
allocation size to PTRDIFF_MAX.
(REQUEST_OUT_OF_RANGE): Remove macro.
(checked_request2size): Change to inline function and limit maximum
requested size to PTRDIFF_MAX.
(__libc_malloc, __libc_realloc, _int_malloc, _int_memalign): Limit
maximum allocation size to PTRDIFF_MAX.
(_mid_memalign): Use _int_memalign call for overflow check.
(__libc_pvalloc): Use __builtin_add_overflow on overflow check.
(__libc_calloc): Use __builtin_mul_overflow for overflow check and
limit maximum requested size to PTRDIFF_MAX.
* malloc/malloc.h (malloc, calloc, realloc, reallocarray, memalign,
valloc, pvalloc): Add __attribute_alloc_size__.
* stdlib/stdlib.h (malloc, realloc, reallocarray, valloc): Likewise.
* malloc/tst-malloc-too-large.c (do_test): Add check for allocation
larger than PTRDIFF_MAX.
* malloc/tst-memalign.c (do_test): Disable -Walloc-size-larger-than=
around tests of malloc with negative sizes.
* malloc/tst-posix_memalign.c (do_test): Likewise.
* malloc/tst-pvalloc.c (do_test): Likewise.
* malloc/tst-valloc.c (do_test): Likewise.
* malloc/tst-reallocarray.c (do_test): Replace call to reallocarray
with resulting size allocation larger than PTRDIFF_MAX with
reallocarray_nowarn.
(reallocarray_nowarn): New function.
* NEWS: Mention the malloc function semantic change.
If an error occurs during the tracing operation, particularly during a
call to lock_and_info() which calls _dl_addr, we may end up calling back
into the malloc-subsystem and relock the loader lock and deadlock. For
all intents and purposes the call to _dl_addr can call any of the malloc
family API functions and so we should disable all tracing before calling
such loader functions. This is similar to the strategy that the new
malloc tracer takes when calling the real malloc, namely that all
tracing ceases at the boundary to the real function and any faults at
that point are the purvue of the library (though the new tracer does
this on a per-thread basis in an MT-safe fashion). Since the new tracer
and the hook deprecation are not yet complete we must fix these issues
where we can.
Tested on x86_64 with no regressions.
Co-authored-by: Kwok Cheung Yeung <kcy@codesourcery.com>
Reviewed-by: DJ Delorie <dj@redhat.com>
Fixes bug 24216. This patch adds security checks for bk and bk_nextsize pointers
of chunks in large bin when inserting chunk from unsorted bin. It was possible
to write the pointer to victim (newly inserted chunk) to arbitrary memory
locations if bk or bk_nextsize pointers of the next large bin chunk
got corrupted.
One group of warnings seen with -Wextra is warnings for static or
inline not at the start of a declaration (-Wold-style-declaration).
This patch fixes various such cases for inline, ensuring it comes at
the start of the declaration (after any static). A common case of the
fix is "static inline <type> __always_inline"; the definition of
__always_inline starts with __inline, so the natural change is to
"static __always_inline <type>". Other cases of the warning may be
harder to fix (one pattern is a function definition that gets
rewritten to be static by an including file, "#define funcname static
wrapped_funcname" or similar), but it seems worth fixing these cases
with inline anyway.
Tested for x86_64.
* elf/dl-load.h (_dl_postprocess_loadcmd): Use __always_inline
before return type, without separate inline.
* elf/dl-tunables.c (maybe_enable_malloc_check): Likewise.
* elf/dl-tunables.h (tunable_is_name): Likewise.
* malloc/malloc.c (do_set_trim_threshold): Likewise.
(do_set_top_pad): Likewise.
(do_set_mmap_threshold): Likewise.
(do_set_mmaps_max): Likewise.
(do_set_mallopt_check): Likewise.
(do_set_perturb_byte): Likewise.
(do_set_arena_test): Likewise.
(do_set_arena_max): Likewise.
(do_set_tcache_max): Likewise.
(do_set_tcache_count): Likewise.
(do_set_tcache_unsorted_limit): Likewise.
* nis/nis_subr.c (count_dots): Likewise.
* nptl/allocatestack.c (advise_stack_range): Likewise.
* sysdeps/ieee754/dbl-64/s_sin.c (do_cos): Likewise.
(do_sin): Likewise.
(reduce_sincos): Likewise.
(do_sincos): Likewise.
* sysdeps/unix/sysv/linux/x86/elision-conf.c
(do_set_elision_enable): Likewise.
(TUNABLE_CALLBACK_FNDECL): Likewise.
One of the warnings that appears with -Wextra is "ordered comparison
of pointer with integer zero" in malloc.c:tcache_get, for the
assertion:
assert (tcache->entries[tc_idx] > 0);
Indeed, a "> 0" comparison does not make sense for
tcache->entries[tc_idx], which is a pointer. My guess is that
tcache->counts[tc_idx] is what's intended here, and this patch changes
the assertion accordingly.
Tested for x86_64.
* malloc/malloc.c (tcache_get): Compare tcache->counts[tc_idx]
with 0, not tcache->entries[tc_idx].
Commit 6923f6db1e ("malloc: Use current
(C11-style) atomics for fastbin access") caused a substantial
performance regression on POWER and Aarch64, and the old atomics,
while hard to prove correct, seem to work in practice.
This commit removes the custom memcpy implementation from _int_realloc
for small chunk sizes. The ncopies variable has the wrong type, and
an integer wraparound could cause the existing code to copy too few
elements (leaving the new memory region mostly uninitialized).
Therefore, removing this code fixes bug 24027.
This one tests for BZ#23907 where the double free
test didn't check the tcache bin bounds before dereferencing
the bin.
[BZ #23907]
* malloc/tst-tcfree3.c: New.
* malloc/Makefile: Add it.
The previous check could read beyond the end of the tcache entry
array. If the e->key == tcache cookie check happened to pass, this
would result in crashes.
This commit is in preparation of turning the macro into a proper
function. The output arguments of the macro were in fact unused.
Also clean up uses of __builtin_expect.
On Thu, Jan 11, 2018 at 3:50 PM, Florian Weimer <fweimer@redhat.com> wrote:
> On 11/07/2017 04:27 PM, Istvan Kurucsai wrote:
>>
>> + next = chunk_at_offset (victim, size);
>
>
> For new code, we prefer declarations with initializers.
Noted.
>> + if (__glibc_unlikely (chunksize_nomask (victim) <= 2 * SIZE_SZ)
>> + || __glibc_unlikely (chunksize_nomask (victim) >
>> av->system_mem))
>> + malloc_printerr("malloc(): invalid size (unsorted)");
>> + if (__glibc_unlikely (chunksize_nomask (next) < 2 * SIZE_SZ)
>> + || __glibc_unlikely (chunksize_nomask (next) >
>> av->system_mem))
>> + malloc_printerr("malloc(): invalid next size (unsorted)");
>> + if (__glibc_unlikely ((prev_size (next) & ~(SIZE_BITS)) !=
>> size))
>> + malloc_printerr("malloc(): mismatching next->prev_size
>> (unsorted)");
>
>
> I think this check is redundant because prev_size (next) and chunksize
> (victim) are loaded from the same memory location.
I'm fairly certain that it compares mchunk_size of victim against
mchunk_prev_size of the next chunk, i.e. the size of victim in its
header and footer.
>> + if (__glibc_unlikely (bck->fd != victim)
>> + || __glibc_unlikely (victim->fd != unsorted_chunks (av)))
>> + malloc_printerr("malloc(): unsorted double linked list
>> corrupted");
>> + if (__glibc_unlikely (prev_inuse(next)))
>> + malloc_printerr("malloc(): invalid next->prev_inuse
>> (unsorted)");
>
>
> There's a missing space after malloc_printerr.
Noted.
> Why do you keep using chunksize_nomask? We never investigated why the
> original code uses it. It may have been an accident.
You are right, I don't think it makes a difference in these checks. So
the size local can be reused for the checks against victim. For next,
leaving it as such avoids the masking operation.
> Again, for non-main arenas, the checks against av->system_mem could be made
> tighter (against the heap size). Maybe you could put the condition into a
> separate inline function?
We could also do a chunk boundary check similar to what I proposed in
the thread for the first patch in the series to be even more strict.
I'll gladly try to implement either but believe that refining these
checks would bring less benefits than in the case of the top chunk.
Intra-arena or intra-heap overlaps would still be doable here with
unsorted chunks and I don't see any way to counter that besides more
generic measures like randomizing allocations and your metadata
encoding patches.
I've attached a revised version with the above comments incorporated
but without the refined checks.
Thanks,
Istvan
From a12d5d40fd7aed5fa10fc444dcb819947b72b315 Mon Sep 17 00:00:00 2001
From: Istvan Kurucsai <pistukem@gmail.com>
Date: Tue, 16 Jan 2018 14:48:16 +0100
Subject: [PATCH v2 1/1] malloc: Additional checks for unsorted bin integrity
I.
Ensure the following properties of chunks encountered during binning:
- victim chunk has reasonable size
- next chunk has reasonable size
- next->prev_size == victim->size
- valid double linked list
- PREV_INUSE of next chunk is unset
* malloc/malloc.c (_int_malloc): Additional binning code checks.
The House of Force is a well-known technique to exploit heap
overflow. In essence, this exploit takes three steps:
1. Overwrite the size of top chunk with very large value (e.g. -1).
2. Request x bytes from top chunk. As the size of top chunk
is corrupted, x can be arbitrarily large and top chunk will
still be offset by x.
3. The next allocation from top chunk will thus be controllable.
If we verify the size of top chunk at step 2, we can stop such attack.
The __libc_freeres framework does not extend to non-libc.so objects.
This causes problems in general for valgrind and mtrace detecting
unfreed objects in both libdl.so and libpthread.so. This change is
a pre-requisite to properly moving the malloc hooks out of malloc
since such a move now requires precise accounting of all allocated
data before destructors are run.
This commit adds a proper hook in libc.so.6 for both libdl.so and
for libpthread.so, this ensures that shm-directory.c which uses
freeit () to free memory is called properly. We also remove the
nptl_freeres hook and fall back to using weak-ref-and-check idiom
for a loaded libpthread.so, thus making this process similar for
all DSOs.
Lastly we follow best practice and use explicit free calls for
both libdl.so and libpthread.so instead of the generic hook process
which has undefined order.
Tested on x86_64 with no regressions.
Signed-off-by: DJ Delorie <dj@redhat.com>
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
This patch mechanically removes all remaining uses, and the
definitions, of the following libio name aliases:
name replaced with
---- -------------
_IO_FILE FILE
_IO_fpos_t __fpos_t
_IO_fpos64_t __fpos64_t
_IO_size_t size_t
_IO_ssize_t ssize_t or __ssize_t
_IO_off_t off_t
_IO_off64_t off64_t
_IO_pid_t pid_t
_IO_uid_t uid_t
_IO_wint_t wint_t
_IO_va_list va_list or __gnuc_va_list
_IO_BUFSIZ BUFSIZ
_IO_cookie_io_functions_t cookie_io_functions_t
__io_read_fn cookie_read_function_t
__io_write_fn cookie_write_function_t
__io_seek_fn cookie_seek_function_t
__io_close_fn cookie_close_function_t
I used __fpos_t and __fpos64_t instead of fpos_t and fpos64_t because
the definitions of fpos_t and fpos64_t depend on the largefile mode.
I used __ssize_t and __gnuc_va_list in a handful of headers where
namespace cleanliness might be relevant even though they're
internal-use-only. In all other cases, I used the public-namespace
name.
There are a tiny handful of places where I left a use of 'struct _IO_FILE'
alone, because it was being used together with 'struct _IO_FILE_plus'
or 'struct _IO_FILE_complete' in the same arithmetic expression.
Because this patch was almost entirely done with search and replace, I
may have introduced indentation botches. I did proofread the diff,
but I may have missed something.
The ChangeLog below calls out all of the places where this was not a
pure search-and-replace change.
Installed stripped libraries and executables are unchanged by this patch,
except that some assertions in vfscanf.c change line numbers.
* libio/libio.h (_IO_FILE): Delete; all uses changed to FILE.
(_IO_fpos_t): Delete; all uses changed to __fpos_t.
(_IO_fpos64_t): Delete; all uses changed to __fpos64_t.
(_IO_size_t): Delete; all uses changed to size_t.
(_IO_ssize_t): Delete; all uses changed to ssize_t or __ssize_t.
(_IO_off_t): Delete; all uses changed to off_t.
(_IO_off64_t): Delete; all uses changed to off64_t.
(_IO_pid_t): Delete; all uses changed to pid_t.
(_IO_uid_t): Delete; all uses changed to uid_t.
(_IO_wint_t): Delete; all uses changed to wint_t.
(_IO_va_list): Delete; all uses changed to va_list or __gnuc_va_list.
(_IO_BUFSIZ): Delete; all uses changed to BUFSIZ.
(_IO_cookie_io_functions_t): Delete; all uses changed to
cookie_io_functions_t.
(__io_read_fn): Delete; all uses changed to cookie_read_function_t.
(__io_write_fn): Delete; all uses changed to cookie_write_function_t.
(__io_seek_fn): Delete; all uses changed to cookie_seek_function_t.
(__io_close_fn): Delete: all uses changed to cookie_close_function_t.
* libio/iofopncook.c: Remove unnecessary forward declarations.
* libio/iolibio.h: Correct outdated commentary.
* malloc/malloc.c (__malloc_stats): Remove unnecessary casts.
* stdio-common/fxprintf.c (__fxprintf_nocancel):
Remove unnecessary casts.
* stdio-common/getline.c: Use _IO_getdelim directly.
Don't redefine ssize_t.
* stdio-common/printf_fp.c, stdio_common/printf_fphex.c
* stdio-common/printf_size.c: Don't redefine size_t or FILE.
Remove outdated comments.
* stdio-common/vfscanf.c: Don't redefine va_list.
malloc_stats means to disable cancellation for writes to stderr while
it runs, but it restores stderr->_flags2 with |= instead of =, so what
it actually does is disable cancellation on stderr permanently.
[BZ #22830]
* malloc/malloc.c (__malloc_stats): Restore stderr->_flags2
correctly.
* malloc/tst-malloc-stats-cancellation.c: New test case.
* malloc/Makefile: Add new test case.
This avoids assert definition conflicts if some of the headers used by
malloc.c happens to include assert.h. Malloc still needs a malloc-avoiding
implementation, which we get by redirecting __assert_fail to malloc's
__malloc_assert.
* malloc/malloc.c: Include <assert.h>.
(assert): Do not define.
[!defined NDEBUG] (__assert_fail): Define to __malloc_assert.
When posix_memalign is called with an alignment less than MALLOC_ALIGNMENT
and a requested size close to SIZE_MAX, it falls back to malloc code
(because the alignment of a block returned by malloc is sufficient to
satisfy the call). In this case, an integer overflow in _int_malloc leads
to posix_memalign incorrectly returning successfully.
Upon fixing this and writing a somewhat thorough regression test, it was
discovered that when posix_memalign is called with an alignment larger than
MALLOC_ALIGNMENT (so it uses _int_memalign instead) and a requested size
close to SIZE_MAX, a different integer overflow in _int_memalign leads to
posix_memalign incorrectly returning successfully.
Both integer overflows affect other memory allocation functions that use
_int_malloc (one affected malloc in x86) or _int_memalign as well.
This commit fixes both integer overflows. In addition to this, it adds a
regression test to guard against false successful allocations by the
following memory allocation functions when called with too-large allocation
sizes and, where relevant, various valid alignments:
malloc, realloc, calloc, reallocarray, memalign, posix_memalign,
aligned_alloc, valloc, and pvalloc.
This patch increases timeouts on three tests I observed timing out on
slow systems.
* malloc/tst-malloc-tcache-leak.c (TIMEOUT): Define to 50.
* posix/tst-glob-tilde.c (TIMEOUT): Define to 200.
* resolv/tst-resolv-res_ninit.c (TIMEOUT): Define to 50.
POSIX explicitly says that applications should check errno only after
failure, so the errno value can be clobbered on success as long as it
is not set to zero.
Changelog:
[BZ #22611]
* malloc/tst-realloc.c (do_test): Remove the test checking that errno
is unchanged on success.
When the per-thread cache is enabled, __libc_malloc uses request2size (which
does not perform an overflow check) to calculate the chunk size from the
requested allocation size. This leads to an integer overflow causing malloc
to incorrectly return the last successfully allocated block when called with
a very large size argument (close to SIZE_MAX).
This commit uses checked_request2size instead, removing the overflow.
It does not make sense to register separate cleanup functions for arena
and tcache since they're always going to be called together. Call the
tcache cleanup function from within arena_thread_freeres since it at
least makes the order of those cleanups clear in the code.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Update all sourceware links to https. The website redirects
everything to https anyway so let the web server do a bit less work.
The only reference that remains unchanged is the one in the old
ChangeLog, since it didn't seem worth changing it.
* NEWS: Update sourceware link to https.
* configure.ac: Likewise.
* crypt/md5test-giant.c: Likewise.
* dlfcn/bug-atexit1.c: Likewise.
* dlfcn/bug-atexit2.c: Likewise.
* localedata/README: Likewise.
* malloc/tst-mallocfork.c: Likewise.
* manual/install.texi: Likewise.
* nptl/tst-pthread-getattr.c: Likewise.
* stdio-common/tst-fgets.c: Likewise.
* stdio-common/tst-fwrite.c: Likewise.
* sunrpc/Makefile: Likewise.
* sysdeps/arm/armv7/multiarch/memcpy_impl.S: Likewise.
* wcsmbs/tst-mbrtowc2.c: Likewise.
* configure: Regenerate.
* INSTALL: Regenerate.
This commit adds a "subheaps" field to the malloc_info output that
shows the number of heaps that were allocated to extend a non-main
arena.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
This patch adds a single-threaded fast path to malloc, realloc,
calloc and memalloc. When we're single-threaded, we can bypass
arena_get (which always locks the arena it returns) and just use
the main arena. Also avoid retrying a different arena since
there is just the main arena.
* malloc/malloc.c (__libc_malloc): Add SINGLE_THREAD_P path.
(__libc_realloc): Likewise.
(_mid_memalign): Likewise.
(__libc_calloc): Likewise.
This patch adds single-threaded fast paths to _int_free.
Bypass the explicit locking for larger allocations.
* malloc/malloc.c (_int_free): Add SINGLE_THREAD_P fast paths.
This patch fixes a deadlock in the fastbin consistency check.
If we fail the fast check due to concurrent modifications to
the next chunk or system_mem, we should not lock if we already
have the arena lock. Simplify the check to make it obviously
correct.
* malloc/malloc.c (_int_free): Fix deadlock bug in consistency check.
The current malloc initialization is quite convoluted. Instead of
sometimes calling malloc_consolidate from ptmalloc_init, call
malloc_init_state early so that the main_arena is always initialized.
The special initialization can now be removed from malloc_consolidate.
This also fixes BZ #22159.
Check all calls to malloc_consolidate and remove calls that are
redundant initialization after ptmalloc_init, like in int_mallinfo
and __libc_mallopt (but keep the latter as consolidation is required for
set_max_fast). Update comments to improve clarity.
Remove impossible initialization check from _int_malloc, fix assert
in do_check_malloc_state to ensure arena->top != 0. Fix the obvious bugs
in do_check_free_chunk and do_check_remalloced_chunk to enable single
threaded malloc debugging (do_check_malloc_state is not thread safe!).
[BZ #22159]
* malloc/arena.c (ptmalloc_init): Call malloc_init_state.
* malloc/malloc.c (do_check_free_chunk): Fix build bug.
(do_check_remalloced_chunk): Fix build bug.
(do_check_malloc_state): Add assert that checks arena->top.
(malloc_consolidate): Remove initialization.
(int_mallinfo): Remove call to malloc_consolidate.
(__libc_mallopt): Clarify why malloc_consolidate is needed.
Currently free typically uses 2 atomic operations per call. The have_fastchunks
flag indicates whether there are recently freed blocks in the fastbins. This
is purely an optimization to avoid calling malloc_consolidate too often and
avoiding the overhead of walking all fast bins even if all are empty during a
sequence of allocations. However using catomic_or to update the flag is
completely unnecessary since it can be changed into a simple boolean and
accessed using relaxed atomics. There is no change in multi-threaded behaviour
given the flag is already approximate (it may be set when there are no blocks in
any fast bins, or it may be clear when there are free blocks that could be
consolidated).
Performance of malloc/free improves by 27% on a simple benchmark on AArch64
(both single and multithreaded). The number of load/store exclusive instructions
is reduced by 33%. Bench-malloc-thread speeds up by ~3% in all cases.
* malloc/malloc.c (FASTCHUNKS_BIT): Remove.
(have_fastchunks): Remove.
(clear_fastchunks): Remove.
(set_fastchunks): Remove.
(malloc_state): Add have_fastchunks.
(malloc_init_state): Use have_fastchunks.
(do_check_malloc_state): Remove incorrect invariant checks.
(_int_malloc): Use have_fastchunks.
(_int_free): Likewise.
(malloc_consolidate): Likewise.
The functions tcache_get and tcache_put show up in profiles as they
are a critical part of the tcache code. Inline them to give tcache
a 16% performance gain. Since this improves multi-threaded cases
as well, it helps offset any potential performance loss due to adding
single-threaded fast paths.
* malloc/malloc.c (tcache_put): Inline.
(tcache_get): Inline.
Since glibc 2.24, __malloc_initialize_hook is a compat symbol. As a
result, the link editor does not export a definition of
__malloc_initialize_hook from the main program, so that it no longer
interposes the variable definition in libc.so. Specifying the symbol
version restores the exported symbol.
realloc_check has
unsigned char *magic_p;
...
__libc_lock_lock (main_arena.mutex);
const mchunkptr oldp = mem2chunk_check (oldmem, &magic_p);
__libc_lock_unlock (main_arena.mutex);
if (!oldp)
malloc_printerr ("realloc(): invalid pointer");
...
if (newmem == NULL)
*magic_p ^= 0xFF;
with
static void malloc_printerr(const char *str) __attribute__ ((noreturn));
GCC 7 -O3 warns
hooks.c: In function ‘realloc_check’:
hooks.c:352:14: error: ‘magic_p’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
*magic_p ^= 0xFF;
due to the GCC bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82090
This patch silences GCC 7 by using DIAG_IGNORE_NEEDS_COMMENT.
[BZ #22052]
* malloc/hooks.c (realloc_check): Use DIAG_IGNORE_NEEDS_COMMENT
to silence -O3 -Wall warning with GCC 7.
The malloc tcache added in 2.26 will leak all of the elements remaining
in the cache and the cache structure itself when a thread exits. The
defect is that we do not set tcache_shutting_down early enough, and the
thread simply recreates the tcache and places the elements back onto a
new tcache which is subsequently lost as the thread exits (unfreed
memory). The fix is relatively simple, move the setting of
tcache_shutting_down earlier in tcache_thread_freeres. We add a test
case which uses mallinfo and some heuristics to look for unaccounted for
memory usage between the start and end of a thread start/join loop. It
is very reliable at detecting that there is a leak given the number of
iterations. Without the fix the test will consume 122MiB of leaked
memory.
Problem reported by Florian Weimer [1] and solution suggested by
Andreas Schwab [2]. It also set the same buffer size independent
of architecture max_align_t size.
Checked on x86_64-linux-gnu and i686-linux-gnu.
* lib/malloc/scratch_buffer.h (struct scratch_buffer):
Use an union instead of a max_align_t array for __space,
so that __space is the same size on all platforms.
* malloc/scratch_buffer_grow_preserve.c
(__libc_scratch_buffer_grow_preserve): Likewise.
[1] https://sourceware.org/ml/libc-alpha/2017-09/msg00693.html
[2] https://sourceware.org/ml/libc-alpha/2017-09/msg00695.html
This patch syncs the scratch_buffer grom gnulib commit 3866ef6 with
GLIBC code.
Checked on x86_64-linux-gnu and on a build using build-many-glibcs.py
for all major architectures.
* include/scratch_buffer.h (scratch_buffer): Use a C99 align method
instead of GCC extension.
* malloc/scratch_buffer_grow.c [!_LIBC]: Include libc-config.h.
* malloc/scratch_buffer_grow_preserve.c [!_LIBC]: Likewise.
* malloc/scratch_buffer_set_array_size.c [!_LIBC]: Likewise.
* include/shlib-compat.h (TEST_COMPAT): New Macro.
* malloc/tst-mallocstate.c: Convert from test-skeleton
to test-driver. Ifdef code using TEST_COMPAT macro.
* math/test-matherr-2.c: Ifdef test using TEST_COMPAT macro.
* math/test-matherr.c: Likewise.
Clean up calls to malloc_printerr and trim its argument list.
This also removes a few bits of work done before calling
malloc_printerr (such as unlocking operations).
The tunable/environment variable still enables the lightweight
additional malloc checking, but mallopt (M_CHECK_ACTION)
no longer has any effect.
__stack_chk_fail is called on corrupted stack. Stack backtrace is very
unreliable against corrupted stack. __libc_message is changed to accept
enum __libc_message_action and call BEFORE_ABORT only if action includes
do_backtrace. __fortify_fail_abort is added to avoid backtrace from
__stack_chk_fail.
[BZ #12189]
* debug/Makefile (CFLAGS-tst-ssp-1.c): New.
(tests): Add tst-ssp-1 if -fstack-protector works.
* debug/fortify_fail.c: Include <stdbool.h>.
(_fortify_fail_abort): New function.
(__fortify_fail): Call _fortify_fail_abort.
(__fortify_fail_abort): Add a hidden definition.
* debug/stack_chk_fail.c: Include <stdbool.h>.
(__stack_chk_fail): Call __fortify_fail_abort, instead of
__fortify_fail.
* debug/tst-ssp-1.c: New file.
* include/stdio.h (__libc_message_action): New enum.
(__libc_message): Replace int with enum __libc_message_action.
(__fortify_fail_abort): New hidden prototype.
* malloc/malloc.c (malloc_printerr): Update __libc_message calls.
* sysdeps/posix/libc_fatal.c (__libc_message): Replace int
with enum __libc_message_action. Call BEFORE_ABORT only if
action includes do_backtrace.
(__libc_fatal): Update __libc_message call.
GCC 7 changed the definition of max_align_t on i386:
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=9b5c49ef97e63cc63f1ffa13baf771368105ebe2
As a result, glibc malloc no longer returns memory blocks which are as
aligned as max_align_t requires.
This causes malloc/tst-malloc-thread-fail to fail with an error like this
one:
error: allocation function 0, size 144 not aligned to 16
This patch moves the MALLOC_ALIGNMENT definition to <malloc-alignment.h>
and increases the malloc alignment to 16 for i386.
[BZ #21120]
* malloc/malloc-internal.h (MALLOC_ALIGNMENT): Moved to ...
* sysdeps/generic/malloc-alignment.h: Here. New file.
* sysdeps/i386/malloc-alignment.h: Likewise.
* sysdeps/generic/malloc-machine.h: Include <malloc-alignment.h>.
According to ISO C11, section 6.5.3.3 "Unary arithmetic operators", the
result of the ~ operator is the bitwise complement of its (promoted)
operand.
This can lead to a comparison of a char with another integer type.
Tested on powerpc, powerpc64 and powerpc64le.
* malloc/tst-alloc_buffer.c (test_misaligned): Cast to char
before comparing with another char.
This commit adds fixed-size allocation buffers. The primary use
case is in NSS modules, where dynamically sized data is stored
in a fixed-size buffer provided by the caller.
Other uses include a replacement of mempcpy cascades (which is
safer due to the size checking inherent to allocation buffers).
The TUNABLE_SET_VALUE and family of macros (and my later attempt to
add a TUNABLE_GET) never quite went together very well because the
overall interface was not clearly defined. This patch is an attempt
to do just that.
This patch consolidates the API to two simple sets of macros,
TUNABLE_GET* and TUNABLE_SET*. If TUNABLE_NAMESPACE is defined,
TUNABLE_GET takes just the tunable name, type and a (optionally NULL)
callback function to get the value of the tunable. The callback
function, if non-NULL, is called if the tunable was externally set
(i.e. via GLIBC_TUNABLES or any future mechanism). For example:
val = TUNABLE_GET (check, int32_t, check_callback)
returns the value of the glibc.malloc.check tunable (assuming
TUNABLE_NAMESPACE is set to malloc) as an int32_t into VAL after
calling check_callback.
Likewise, TUNABLE_SET can be used to set the value of the tunable,
although this is currently possible only in the dynamic linker before
it relocates itself. For example:
TUNABLE_SET (check, int32_t, 2)
will set glibc.malloc.check to 2. Of course, this is not possible
since we set (or read) glibc.malloc.check long after it is relocated.
To access or set a tunable outside of TUNABLE_NAMESPACE, use the
TUNABLE_GET_FULL and TUNABLE_SET_FULL macros, which have the following
prototype:
TUNABLE_GET_FULL (glibc, tune, hwcap_mask, uint64_t, NULL)
TUNABLE_SET_FULL (glibc, tune, hwcap_mask, uint64_t, 0xffff)
In future the tunable list may get split into mutable and immutable
tunables where mutable tunables can be modified by the library and
userspace after relocation as well and TUNABLE_SET will be more useful
than it currently is. However whenever we actually do that split, we
will have to ensure that the mutable tunables are protected with
locks.
* elf/Versions (__tunable_set_val): Rename to __tunable_get_val.
* elf/dl-tunables.c: Likewise.
(do_tunable_update_val): New function.
(__tunable_set_val): New function.
(__tunable_get_val): Call CB only if the tunable was externally
initialized.
(tunables_strtoul): Replace strval with initialized.
* elf/dl-tunables.h (strval): Replace with a bool initialized.
(TUNABLE_ENUM_NAME, TUNABLE_ENUM_NAME1): Adjust names to
prevent collision.
(__tunable_set_val): New function.
(TUNABLE_GET, TUNABLE_GET_FULL): New macros.
(TUNABLE_SET, TUNABLE_SET_FULL): Likewise.
(TUNABLE_SET_VAL): Remove.
(TUNABLE_SET_VAL_WITH_CALLBACK): Likewise.
* README.tunables: Document the new macros.
* malloc/arena.c (ptmalloc_init): Adjust.
This is intended as a type-safe alternative to obstacks and
hand-written realloc constructs. The implementation avoids
writing function pointers to the heap.
This patch adds a new build module called 'testsuite'.
IS_IN (testsuite) implies _ISOMAC, as do IS_IN_build and __cplusplus
(which means several ad-hoc tests for __cplusplus can go away).
libc-symbols.h now suppresses almost all of *itself* when _ISOMAC is
defined; in particular, _ISOMAC mode does not get config.h
automatically anymore.
There are still quite a few tests that need to see internal gunk of
one variety or another. For them, we now have 'tests-internal' and
'test-internal-extras'; files in this category will still be compiled
with MODULE_NAME=nonlib, and everything proceeds as it always has.
The bulk of this patch is moving tests from 'tests' to
'tests-internal'. There is also 'tests-static-internal', which has
the same effect on files in 'tests-static', and 'modules-names-tests',
which has the *inverse* effect on files in 'modules-names' (it's
inverted because most of the things in modules-names are *not* tests).
For both of these, the file must appear in *both* the new variable and
the old one.
There is also now a special case for when libc-symbols.h is included
without MODULE_NAME being defined at all. (This happens during the
creation of libc-modules.h, and also when preprocessing Versions
files.) When this happens, IS_IN is set to be always false and
_ISOMAC is *not* defined, which was the status quo, but now it's
explicit.
The remaining changes to C source files in this patch seemed likely to
cause problems in the absence of the main change. They should be
relatively self-explanatory. In a few cases I duplicated a definition
from an internal header rather than move the test to tests-internal;
this was a judgement call each time and I'm happy to change those
however reviewers feel is more appropriate.
* Makerules: New subdir configuration variables 'tests-internal'
and 'test-internal-extras'. Test files in these categories will
still be compiled with MODULE_NAME=nonlib. Test files in the
existing categories (tests, xtests, test-srcs, test-extras) are
now compiled with MODULE_NAME=testsuite.
New subdir configuration variable 'modules-names-tests'. Files
which are in both 'modules-names' and 'modules-names-tests' will
be compiled with MODULE_NAME=testsuite instead of
MODULE_NAME=extramodules.
(gen-as-const-headers): Move to tests-internal.
(do-tests-clean, common-mostlyclean): Support tests-internal.
* Makeconfig (built-modules): Add testsuite.
* Makefile: Change libof-check-installed-headers-c and
libof-check-installed-headers-cxx to 'testsuite'.
* Rules: Likewise. Support tests-internal.
* benchtests/strcoll-inputs/filelist#en_US.UTF-8:
Remove extra-modules.mk.
* config.h.in: Don't check for __OPTIMIZE__ or __FAST_MATH__ here.
* include/libc-symbols.h: Move definitions of _GNU_SOURCE,
PASTE_NAME, PASTE_NAME1, IN_MODULE, IS_IN, and IS_IN_LIB to the
very top of the file and rationalize their order.
If MODULE_NAME is not defined at all, define IS_IN to always be
false, and don't define _ISOMAC.
If any of IS_IN (testsuite), IS_IN_build, or __cplusplus are
true, define _ISOMAC and suppress everything else in this file,
starting with the inclusion of config.h.
Do check for inappropriate definitions of __OPTIMIZE__ and
__FAST_MATH__ here, but only if _ISOMAC is not defined.
Correct some out-of-date commentary.
* include/math.h: If _ISOMAC is defined, undefine NO_LONG_DOUBLE
and _Mlong_double_ before including math.h.
* include/string.h: If _ISOMAC is defined, don't expose
_STRING_ARCH_unaligned. Move a comment to a more appropriate
location.
* include/errno.h, include/stdio.h, include/stdlib.h, include/string.h
* include/time.h, include/unistd.h, include/wchar.h: No need to
check __cplusplus nor use __BEGIN_DECLS/__END_DECLS.
* misc/sys/cdefs.h (__NTHNL): New macro.
* sysdeps/m68k/m680x0/fpu/bits/mathinline.h
(__m81_defun): Use __NTHNL to avoid errors with GCC 6.
* elf/tst-env-setuid-tunables.c: Include config.h with _LIBC
defined, for HAVE_TUNABLES.
* inet/tst-checks-posix.c: No need to define _ISOMAC.
* intl/tst-gettext2.c: Provide own definition of N_.
* math/test-signgam-finite-c99.c: No need to define _ISOMAC.
* math/test-signgam-main.c: No need to define _ISOMAC.
* stdlib/tst-strtod.c: Convert to test-driver. Split locale_test to...
* stdlib/tst-strtod1i.c: ...this new file.
* stdlib/tst-strtod5.c: Convert to test-driver and add copyright notice.
Split tests of __strtod_internal to...
* stdlib/tst-strtod5i.c: ...this new file.
* string/test-string.h: Include stdint.h. Duplicate definition of
inhibit_loop_to_libcall here (from libc-symbols.h).
* string/test-strstr.c: Provide dummy definition of
libc_hidden_builtin_def when including strstr.c.
* sysdeps/ia64/fpu/libm-symbols.h: Suppress entire file in _ISOMAC
mode; no need to test __STRICT_ANSI__ nor __cplusplus as well.
* sysdeps/x86_64/fpu/math-tests-arch.h: Include cpu-features.h.
Don't include init-arch.h.
* sysdeps/x86_64/multiarch/test-multiarch.h: Include cpu-features.h.
Don't include init-arch.h.
* elf/Makefile: Move tst-ptrguard1-static, tst-stackguard1-static,
tst-tls1-static, tst-tls2-static, tst-tls3-static, loadtest,
unload, unload2, circleload1, neededtest, neededtest2,
neededtest3, neededtest4, tst-tls1, tst-tls2, tst-tls3,
tst-tls6, tst-tls7, tst-tls8, tst-dlmopen2, tst-ptrguard1,
tst-stackguard1, tst-_dl_addr_inside_object, and all of the
ifunc tests to tests-internal.
Don't add $(modules-names) to test-extras.
* inet/Makefile: Move tst-inet6_scopeid_pton to tests-internal.
Add tst-deadline to tests-static-internal.
* malloc/Makefile: Move tst-mallocstate and tst-scratch_buffer to
tests-internal.
* misc/Makefile: Move tst-atomic and tst-atomic-long to tests-internal.
* nptl/Makefile: Move tst-typesizes, tst-rwlock19, tst-sem11,
tst-sem12, tst-sem13, tst-barrier5, tst-signal7, tst-tls3,
tst-tls3-malloc, tst-tls5, tst-stackguard1, tst-sem11-static,
tst-sem12-static, and tst-stackguard1-static to tests-internal.
Link tests-internal with libpthread also.
Don't add $(modules-names) to test-extras.
* nss/Makefile: Move tst-field to tests-internal.
* posix/Makefile: Move bug-regex5, bug-regex20, bug-regex33,
tst-rfc3484, tst-rfc3484-2, and tst-rfc3484-3 to tests-internal.
* stdlib/Makefile: Move tst-strtod1i, tst-strtod3, tst-strtod4,
tst-strtod5i, tst-tls-atexit, and tst-tls-atexit-nodelete to
tests-internal.
* sunrpc/Makefile: Move tst-svc_register to tests-internal.
* sysdeps/powerpc/Makefile: Move test-get_hwcap and
test-get_hwcap-static to tests-internal.
* sysdeps/unix/sysv/linux/Makefile: Move tst-setgetname to
tests-internal.
* sysdeps/x86_64/fpu/Makefile: Add all libmvec test modules to
modules-names-tests.
cppflags-iterator.mk no longer has anything to do with CPPFLAGS; all
it does is set libof-$(foo) for a list of files. extra-modules.mk
does the same thing, but with a different input variable, and doesn't
let the caller control the module. Therefore, this patch gives
cppflags-iterator.mk a better name, removes extra-modules.mk, and
updates all uses of both.
* extra-modules.mk: Delete file.
* cppflags-iterator.mk: Rename to ...
* libof-iterator.mk: ...this. Adjust comments.
* Makerules, extra-lib.mk, benchtests/Makefile, elf/Makefile
* elf/rtld-Rules, iconv/Makefile, locale/Makefile, malloc/Makefile
* nscd/Makefile, sunrpc/Makefile, sysdeps/s390/Makefile:
Use libof-iterator.mk instead of cppflags-iterator.mk or
extra-modules.mk.
* benchtests/strcoll-inputs/filelist#en_US.UTF-8: Remove
extra-modules.mk and cppflags-iterator.mk, add libof-iterator.mk.
MMap'd memory isn't shrunk without MREMAP, but IIRC this is intentional for
performance reasons. Regardless, this patch tweaks the existing comment to
be more accurate wrt the existing code.
[BZ #21411]
* malloc/malloc.c: Tweak realloc/MREMAP comment to be more accurate.
Fixes a typo introduced in commit
be7991c070. This caused
mallopt(M_ARENA_MAX) as well as the environment variable
MALLOC_ARENA_MAX to not work as intended because it set the
wrong internal parameter.
[BZ #21338]
* malloc/malloc.c: Call do_set_arena_max for M_ARENA_MAX
instead of incorrect do_set_arena_test
The test malloc/tst-interpose-nothread fails on s390x if built
with GCC 7 and glibc commit "Remove the str(n)dup inlines
from string/bits/string2.h. Although inlining"
(ae65d4f3c3) with output:
error: free: 0x3fffdffa010: invalid allocation index: 0 (not less than 0)
The destructor check_for_allocations in malloc/tst-interpose-aux.c is
called twice. One time after the test-child-process has finished successfully
and once after the test-parent-process finishes.
During the latter invocation, allocation_index == 0. GCC 7 is now inlining the
free function and calls unconditionally fail in get_header as
header->allocation_index (type == size_t) is always >= allocation_index (= 0).
Before the mentioned commit above, strdup was replaced by strlen, malloc and
memcpy. The malloc call was also inlined and allocation_index was set to one.
This patch moves the already existing compiler barrier before the invocation
of free.
ChangeLog:
* malloc/tst-interpose-aux.c (check_for_allocations):
Move compiler barrier before free.
Additional check for chunk_size == next->prev->chunk_size in unlink()
2017-03-17 Chris Evans <scarybeasts@gmail.com>
* malloc/malloc.c (unlink): Add consistency check between size and
next->prev->size, to further harden against 1-byte overflows.
posix/wordexp-test.c used libc-internal.h for PTR_ALIGN_DOWN; similar
to what was done with libc-diag.h, I have split the definitions of
cast_to_integer, ALIGN_UP, ALIGN_DOWN, PTR_ALIGN_UP, and PTR_ALIGN_DOWN
to a new header, libc-pointer-arith.h.
It then occurred to me that the remaining declarations in libc-internal.h
are mostly to do with early initialization, and probably most of the
files including it, even in the core code, don't need it anymore. Indeed,
only 19 files actually need what remains of libc-internal.h. 23 others
need libc-diag.h instead, and 12 need libc-pointer-arith.h instead.
No file needs more than one of them, and 16 don't need any of them!
So, with this patch, libc-internal.h stops including libc-diag.h as
well as losing the pointer arithmetic macros, and all including files
are adjusted.
* include/libc-pointer-arith.h: New file. Define
cast_to_integer, ALIGN_UP, ALIGN_DOWN, PTR_ALIGN_UP, and
PTR_ALIGN_DOWN here.
* include/libc-internal.h: Definitions of above macros
moved from here. Don't include libc-diag.h anymore either.
* posix/wordexp-test.c: Include stdint.h and libc-pointer-arith.h.
Don't include libc-internal.h.
* debug/pcprofile.c, elf/dl-tunables.c, elf/soinit.c, io/openat.c
* io/openat64.c, misc/ptrace.c, nptl/pthread_clock_gettime.c
* nptl/pthread_clock_settime.c, nptl/pthread_cond_common.c
* string/strcoll_l.c, sysdeps/nacl/brk.c
* sysdeps/unix/clock_settime.c
* sysdeps/unix/sysv/linux/i386/get_clockfreq.c
* sysdeps/unix/sysv/linux/ia64/get_clockfreq.c
* sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
* sysdeps/unix/sysv/linux/sparc/sparc64/get_clockfreq.c:
Don't include libc-internal.h.
* elf/get-dynamic-info.h, iconv/loop.c
* iconvdata/iso-2022-cn-ext.c, locale/weight.h, locale/weightwc.h
* misc/reboot.c, nis/nis_table.c, nptl_db/thread_dbP.h
* nscd/connections.c, resolv/res_send.c, soft-fp/fmadf4.c
* soft-fp/fmasf4.c, soft-fp/fmatf4.c, stdio-common/vfscanf.c
* sysdeps/ieee754/dbl-64/e_lgamma_r.c
* sysdeps/ieee754/dbl-64/k_rem_pio2.c
* sysdeps/ieee754/flt-32/e_lgammaf_r.c
* sysdeps/ieee754/flt-32/k_rem_pio2f.c
* sysdeps/ieee754/ldbl-128/k_tanl.c
* sysdeps/ieee754/ldbl-128ibm/k_tanl.c
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c
* sysdeps/ieee754/ldbl-96/k_tanl.c, sysdeps/nptl/futex-internal.h:
Include libc-diag.h instead of libc-internal.h.
* elf/dl-load.c, elf/dl-reloc.c, locale/programs/locarchive.c
* nptl/nptl-init.c, string/strcspn.c, string/strspn.c
* malloc/malloc.c, sysdeps/i386/nptl/tls.h
* sysdeps/nacl/dl-map-segments.h, sysdeps/x86_64/atomic-machine.h
* sysdeps/unix/sysv/linux/spawni.c
* sysdeps/x86_64/nptl/tls.h:
Include libc-pointer-arith.h instead of libc-internal.h.
* elf/get-dynamic-info.h, sysdeps/nacl/dl-map-segments.h
* sysdeps/x86_64/atomic-machine.h:
Add multiple include guard.
Quite a few tests include libc-internal.h just for the DIAG_* macros.
Split those macros to their own file, which can be included safely in
_ISOMAC mode. I also moved ignore_value, since it seems logically
related, even though I didn't notice any tests needing it.
Also add -Wnonnull suppressions to two tests that _should_ have them,
but the error is masked when compiling against internal headers.
* include/libc-diag.h: New file. Define ignore_value,
DIAG_PUSH_NEEDS_COMMENT, DIAG_POP_NEEDS_COMMENT,
DIAG_IGNORE_NEEDS_COMMENT, and DIAG_IGNORE_Os_NEEDS_COMMENT here.
* include/libc-internal.h: Definitions of above macros moved from
here. Include libc-diag.h. Add copyright notice.
* malloc/tst-malloc.c, malloc/tst-memcheck.c, malloc/tst-realloc.c
* misc/tst-error1.c, posix/tst-dir.c, stdio-common/bug21.c
* stdio-common/scanf14.c, stdio-common/scanf4.c, stdio-common/scanf7.c
* stdio-common/test-vfprintf.c, stdio-common/tst-printf.c
* stdio-common/tst-printfsz.c, stdio-common/tst-sprintf.c
* stdio-common/tst-unlockedio.c, stdio-common/tstdiomisc.c
* stdlib/bug-getcontext.c, string/tester.c, string/tst-endian.c
* time/tst-strptime2.c, wcsmbs/tst-wcstof.c:
Include libc-diag.h instead of libc-internal.h.
* stdlib/tst-environ.c: Include libc-diag.h. Suppress -Wnonnull for
call to unsetenv (NULL).
* nptl/tst-mutex1.c: Include libc-diag.h. Suppress -Wnonnull for
call to pthread_mutexattr_destroy (NULL).
* crypt/md5.h: Test _LIBC with #if defined, not #if.
* dirent/opendir-tst1.c: Include sys/stat.h.
* dirent/tst-fdopendir.c: Include sys/stat.h.
* dirent/tst-fdopendir2.c: Include stdlib.h.
* dirent/tst-scandir.c: Include stdbool.h.
* elf/tst-auditmod1.c: Include link.h and stddef.h.
* elf/tst-tls15.c: Include stdlib.h.
* elf/tst-tls16.c: Include stdlib.h.
* elf/tst-tls17.c: Include stdlib.h.
* elf/tst-tls18.c: Include stdlib.h.
* iconv/tst-iconv6.c: Include endian.h.
* iconvdata/bug-iconv11.c: Include limits.h.
* io/test-utime.c: Include stdint.h.
* io/tst-faccessat.c: Include sys/stat.h.
* io/tst-fchmodat.c: Include sys/stat.h.
* io/tst-fchownat.c: Include sys/stat.h.
* io/tst-fstatat.c: Include sys/stat.h.
* io/tst-futimesat.c: Include sys/stat.h.
* io/tst-linkat.c: Include sys/stat.h.
* io/tst-mkdirat.c: Include sys/stat.h and stdbool.h.
* io/tst-mkfifoat.c: Include sys/stat.h and stdbool.h.
* io/tst-mknodat.c: Include sys/stat.h and stdbool.h.
* io/tst-openat.c: Include stdbool.h.
* io/tst-readlinkat.c: Include sys/stat.h.
* io/tst-renameat.c: Include sys/stat.h.
* io/tst-symlinkat.c: Include sys/stat.h.
* io/tst-unlinkat.c: Include stdbool.h.
* libio/bug-memstream1.c: Include stdlib.h.
* libio/bug-wmemstream1.c: Include stdlib.h.
* libio/tst-fwrite-error.c: Include stdlib.h.
* libio/tst-memstream1.c: Include stdlib.h.
* libio/tst-memstream2.c: Include stdlib.h.
* libio/tst-memstream3.c: Include stdlib.h.
* malloc/tst-interpose-aux.c: Include stdint.h.
* misc/tst-preadvwritev-common.c: Include sys/stat.h.
* nptl/tst-basic7.c: Include limits.h.
* nptl/tst-cancel25.c: Include pthread.h, not pthreadP.h.
* nptl/tst-cancel4.c: Include stddef.h, limits.h, and sys/stat.h.
* nptl/tst-cancel4_1.c: Include stddef.h.
* nptl/tst-cancel4_2.c: Include stddef.h.
* nptl/tst-cond16.c: Include limits.h.
Use sysconf(_SC_PAGESIZE) instead of __getpagesize.
* nptl/tst-cond18.c: Include limits.h.
Use sysconf(_SC_PAGESIZE) instead of __getpagesize.
* nptl/tst-cond4.c: Include stdint.h.
* nptl/tst-cond6.c: Include stdint.h.
* nptl/tst-stack2.c: Include limits.h.
* nptl/tst-stackguard1.c: Include stddef.h.
* nptl/tst-tls4.c: Include stdint.h. Don't include tls.h.
* nptl/tst-tls4moda.c: Include stddef.h.
Don't include stdio.h, unistd.h, or tls.h.
* nptl/tst-tls4modb.c: Include stddef.h.
Don't include stdio.h, unistd.h, or tls.h.
* nptl/tst-tls5.h: Include stddef.h. Don't include stdlib.h or tls.h.
* posix/tst-getaddrinfo2.c: Include stdio.h.
* posix/tst-getaddrinfo5.c: Include stdio.h.
* posix/tst-pathconf.c: Include sys/stat.h.
* posix/tst-posix_fadvise-common.c: Include stdint.h.
* posix/tst-preadwrite-common.c: Include sys/stat.h.
* posix/tst-regex.c: Include stdint.h.
Don't include spawn.h or spawn_int.h.
* posix/tst-regexloc.c: Don't include spawn.h or spawn_int.h.
* posix/tst-vfork3.c: Include sys/stat.h.
* resolv/tst-bug18665-tcp.c: Include stdlib.h.
* resolv/tst-res_hconf_reorder.c: Include stdlib.h.
* resolv/tst-resolv-search.c: Include stdlib.h.
* stdio-common/tst-fmemopen2.c: Include stdint.h.
* stdio-common/tst-vfprintf-width-prec.c: Include stdlib.h.
* stdlib/test-canon.c: Include sys/stat.h.
* stdlib/tst-tls-atexit.c: Include stdbool.h.
* string/test-memchr.c: Include stdint.h.
* string/tst-cmp.c: Include stdint.h.
* sysdeps/pthread/tst-timer.c: Include stdint.h.
* sysdeps/unix/sysv/linux/tst-sync_file_range.c: Include stdint.h.
* sysdeps/wordsize-64/tst-writev.c: Include limits.h and stdint.h.
* sysdeps/x86_64/fpu/math-tests-arch.h: Include cpu-features.h.
Don't include init-arch.h.
* sysdeps/x86_64/multiarch/test-multiarch.h: Include cpu-features.h.
Don't include init-arch.h.
* sysdeps/x86_64/tst-auditmod10b.c: Include link.h and stddef.h.
* sysdeps/x86_64/tst-auditmod3b.c: Include link.h and stddef.h.
* sysdeps/x86_64/tst-auditmod4b.c: Include link.h and stddef.h.
* sysdeps/x86_64/tst-auditmod5b.c: Include link.h and stddef.h.
* sysdeps/x86_64/tst-auditmod6b.c: Include link.h and stddef.h.
* sysdeps/x86_64/tst-auditmod6c.c: Include link.h and stddef.h.
* sysdeps/x86_64/tst-auditmod7b.c: Include link.h and stddef.h.
* time/clocktest.c: Include stdint.h.
* time/tst-posixtz.c: Include stdint.h.
* timezone/tst-timezone.c: Include stdint.h.
The code to set value passed a tunable_val_t, which when cast to
int32_t on big-endian gives the wrong value. Instead, use
tunable_val_t.numval instead, which can then be safely cast into
int32_t.
This patch increases timeouts on some tests I've observed timing out.
elf/tst-tls13 and iconvdata/tst-loading both dynamically load many
objects and so are slow when testing over NFS. They had timeouts set
from before the default changed from 2 to 20 seconds; this patch
removes those old settings, so effectively increasing the timeout to
20 seconds (from 3 and 10 seconds respectively).
malloc/tst-malloc-thread-fail.c and malloc/tst-mallocfork2.c are slow
on slow systems and so I set a fairly arbitrary 100 second timeout,
which seems to suffice on the system where I saw them timing out.
nss/tst-cancel-getpwuid_r.c and nss/tst-nss-getpwent.c are slow on
systems with a large passwd file; I set timeouts that empirically
worked for me. (It seems tst-cancel-getpwuid_r.c is hitting the
100000 getpwuid_r call limit in my testing, with each call taking a
bit over 0.007 seconds, so 700 seconds for the test.)
* elf/tst-tls13.c (TIMEOUT): Remove.
* iconvdata/tst-loading.c (TIMEOUT): Likewise.
* malloc/tst-malloc-thread-fail.c (TIMEOUT): Increase to 100.
* malloc/tst-mallocfork2.c (TIMEOUT): Define to 100.
* nss/tst-cancel-getpwuid_r.c (TIMEOUT): Define to 900.
* nss/tst-nss-getpwent.c (TIMEOUT): Define to 300.
GCC 7 has a -Walloc-size-larger-than= warning for allocations of half
the address space or more. This causes errors building glibc tests
that deliberately test failure of very large allocations. This patch
arranges for this warning to be ignored around the problematic
function calls.
Tested compilation for aarch64 (GCC mainline) with
build-many-glibcs.py; did execution testing for x86_64 (GCC 5).
* malloc/tst-malloc.c: Include <libc-internal.h>.
(do_test): Disable -Walloc-size-larger-than= around tests of
malloc with negative sizes.
* malloc/tst-mcheck.c: Include <libc-internal.h>.
(do_test): Disable -Walloc-size-larger-than= around tests of
malloc and realloc with negative sizes.
* malloc/tst-realloc.c: Include <libc-internal.h>.
(do_test): Disable -Walloc-size-larger-than= around tests of
realloc with negative sizes.
Read tunables values from the users using the GLIBC_TUNABLES
environment variable. The value of this variable is a colon-separated
list of name=value pairs. So a typical string would look like this:
GLIBC_TUNABLES=glibc.malloc.mmap_threshold=2048:glibc.malloc.trim_threshold=1024
* config.make.in (have-loop-to-function): Define.
* elf/Makefile (CFLAGS-dl-tunables.c): Add
-fno-tree-loop-distribute-patterns.
* elf/dl-tunables.c: Include libc-internals.h.
(GLIBC_TUNABLES): New macro.
(tunables_strdup): New function.
(parse_tunables): New function.
(min_strlen): New function.
(__tunables_init): Use the new functions and macro.
(disable_tunable): Disable tunable from GLIBC_TUNABLES.
* malloc/tst-malloc-usable-tunables.c: New test case.
* malloc/tst-malloc-usable-static-tunables.c: New test case.
* malloc/Makefile (tests, tests-static): Add tests.
The tunables framework allows us to uniformly manage and expose global
variables inside glibc as switches to users. tunables/README has
instructions for glibc developers to add new tunables.
Tunables support can be enabled by passing the --enable-tunables
configure flag to the configure script. This patch only adds a
framework and does not pose any limitations on how tunable values are
read from the user. It also adds environment variables used in malloc
behaviour tweaking to the tunables framework as a PoC of the
compatibility interface.
* manual/install.texi: Add --enable-tunables option.
* INSTALL: Regenerate.
* README.tunables: New file.
* Makeconfig (CPPFLAGS): Define TOP_NAMESPACE.
(before-compile): Generate dl-tunable-list.h early.
* config.h.in: Add HAVE_TUNABLES.
* config.make.in: Add have-tunables.
* configure.ac: Add --enable-tunables option.
* configure: Regenerate.
* csu/init-first.c (__libc_init_first): Move
__libc_init_secure earlier...
* csu/init-first.c (LIBC_START_MAIN):... to here.
Include dl-tunables.h, libc-internal.h.
(LIBC_START_MAIN) [!SHARED]: Initialize tunables for static
binaries.
* elf/Makefile (dl-routines): Add dl-tunables.
* elf/Versions (ld): Add __tunable_set_val to GLIBC_PRIVATE
namespace.
* elf/dl-support (_dl_nondynamic_init): Unset MALLOC_CHECK_
only when !HAVE_TUNABLES.
* elf/rtld.c (process_envvars): Likewise.
* elf/dl-sysdep.c [HAVE_TUNABLES]: Include dl-tunables.h
(_dl_sysdep_start): Call __tunables_init.
* elf/dl-tunable-types.h: New file.
* elf/dl-tunables.c: New file.
* elf/dl-tunables.h: New file.
* elf/dl-tunables.list: New file.
* malloc/tst-malloc-usable-static.c: New test case.
* malloc/Makefile (tests-static): Add it.
* malloc/arena.c [HAVE_TUNABLES]: Include dl-tunables.h.
Define TUNABLE_NAMESPACE.
(DL_TUNABLE_CALLBACK (set_mallopt_check)): New function.
(DL_TUNABLE_CALLBACK_FNDECL): New macro. Use it to define
callback functions.
(ptmalloc_init): Set tunable values.
* scripts/gen-tunables.awk: New file.
* sysdeps/mach/hurd/dl-sysdep.c: Include dl-tunables.h.
(_dl_sysdep_start): Call __tunables_init.
The new test driver in <support/test-driver.c> has feature parity with
the old one. The main difference is that its hooking mechanism is
based on functions and function pointers instead of macros. This
commit also implements a new environment variable, TEST_COREDUMPS,
which disables the code which disables coredumps (that is, it enables
them if the invocation environment has not disabled them).
<test-skeleton.c> defines wrapper functions so that it is possible to
use existing macros with the new-style hook functionality.
This commit changes only a few test cases to the new test driver, to
make sure that it works as expected.
Make mallopt helper functions for each mallopt parameter so that it
can be called consistently in other areas, like setting tunables.
* malloc/malloc.c (do_set_mallopt_check): New function.
(do_set_mmap_threshold): Likewise.
(do_set_mmaps_max): Likewise.
(do_set_top_pad): Likewise.
(do_set_perturb_byte): Likewise.
(do_set_trim_threshold): Likewise.
(do_set_arena_max): Likewise.
(do_set_arena_test): Likewise.
(__libc_mallopt): Use them.
After the removal of __malloc_initialize_hook, newly compiled
Emacs binaries are no longer able to use these interfaces.
malloc_get_state is only used during the Emacs build process,
so we provide a stub implementation only. Existing Emacs binaries
will not call this stub function, but still reference the symbol.
The rewritten tst-mallocstate test constructs a dumped heap
which should approximates what existing Emacs binaries pass
to glibc malloc.
The M_ARENA_MAX and M_ARENA_TEST macros are defined in malloc.c as
well as malloc.h, and the former is unnecessary. This patch removes
the duplicate. Tested on x86_64 to verify that the generated code
remains unchanged barring changed line numbers to __malloc_assert.
* malloc/malloc.c (M_ARENA_TEST, M_ARENA_MAX): Remove.
The M_ARENA_* mallopt parameters are in wide use in production to
control the number of arenas that a long lived process creates and
hence there is no point in stating that this interface is non-public.
Document this interface and remove the obsolete comment.
* manual/memory.texi (M_ARENA_TEST): Add documentation.
(M_ARENA_MAX): Likewise.
* malloc/malloc.c: Remove obsolete comment.
This is a trivial change to add the static tests only to tests-static
and then adding all of tests-static to the tests target to make it
look consistent with some other Makefiles. This avoids having to
duplicate the test names across the two make targets.
* malloc/Makefile (tests): Remove individual static test names
and just add all of tests-static.
Existing interposed mallocs do not define the glibc-internal
fork callbacks (and they should not), so statically interposed
mallocs lead to link failures because the strong reference from
fork pulls in glibc's malloc, resulting in multiple definitions
of malloc-related symbols.
The dynamic linker currently uses __libc_memalign for TLS-related
allocations. The goal is to switch to malloc instead. If the minimal
malloc follows the ABI fundamental alignment, we can assume that malloc
provides this alignment, and thus skip explicit alignment in a few
cases as an optimization.
It was requested on libc-alpha that MALLOC_ALIGNMENT should be used,
although this results in wasted space if MALLOC_ALIGNMENT is larger
than the fundamental alignment. (The dynamic linker cannot assume
that the non-minimal malloc will provide an alignment of
MALLOC_ALIGNMENT; the ABI provides _Alignof (max_align_t) only.)
It is necessary to preserve the invariant that if an arena is
on the free list, it has thread attach count zero. Otherwise,
when arena_thread_freeres sees the zero attach count, it will
add it, and without the invariant, an arena could get pushed
to the list twice, resulting in a cycle.
One possible execution trace looks like this:
Thread 1 examines free list and observes it as empty.
Thread 2 exits and adds its arena to the free list,
with attached_threads == 0).
Thread 1 selects this arena in reused_arena (not from the free list).
Thread 1 increments attached_threads and attaches itself.
(The arena remains on the free list.)
Thread 1 exits, decrements attached_threads,
and adds the arena to the free list.
The final step creates a cycle in the usual way (by overwriting the
next_free member with the former list head, while there is another
list item pointing to the arena structure).
tst-malloc-thread-exit exhibits this issue, but it was only visible
with a debugger because the incorrect fix in bug 19243 removed
the assert from get_free_list.
Right now tilegx is right on the verge of timeout when it runs,
so adding a bit of headroom seems like the right thing; we
see failures when running tests in parallel.
Before this change, the while loop in reused_arena which avoids
returning a corrupt arena would never execute its body if the selected
arena were not corrupt. As a result, result == begin after the loop,
and the function returns NULL, triggering fallback to mmap.
__malloc_initialize_hook is interposed by application code, so
the usual approach to define a compatibility symbol does not work.
This commit adds a new mechanism based on #pragma GCC poison in
<stdc-predef.h>.
For regular mmapped chunks there are two size fields (hence a reduction
by 2 * SIZE_SZ bytes), but for fake chunks, we only have one size field,
so we need to subtract SIZE_SZ bytes.
This was initially reported as Emacs bug 23726.
After the heap rewriting added in commit
4cf6c72fd2 (malloc: Rewrite dumped heap
for compatibility in __malloc_set_state), we can change malloc alignment
for new allocations because the alignment of old allocations no longer
matters.
We need to increase the malloc state version number, so that binaries
containing dumped heaps of the new layout will not try to run on
previous versions of glibc, resulting in obscure crashes.
This commit addresses a failure of tst-malloc-thread-fail on the
affected architectures (32-bit ppc and mips) because the test checks
pointer alignment.
The first SIGUSR1 signal could arrive when sigusr1_sender_pid
was still 0. As a result, kill would send SIGSTOP to the
entire process group. This would cause the test to hang before
printing any output.
This commit also adds a sched_yield to the signal source, so that
it does not flood the parent process with signals it has never a
chance to handle.
Even with these changes, tst-mallocfork2 still fails reliably
after the fix in commit commit 56290d6e76
(Increase fork signal safety for single-threaded processes) is
backed out.
This will allow us to change many aspects of the malloc implementation
while preserving compatibility with existing Emacs binaries.
As a result, existing Emacs binaries will have a larger RSS, and Emacs
needs a few more milliseconds to start. This overhead is specific
to Emacs (and will go away once Emacs switches to its internal malloc).
The new checks to make free and realloc compatible with the dumped heap
are confined to the mmap paths, which are already quite slow due to the
munmap overhead.
This commit weakens some security checks, but only for heap pointers
in the dumped main arena. By default, this area is empty, so those
checks are as effective as before.
This provides a band-aid and addresses the scenario where fork is
called from a signal handler while the process is in the malloc
subsystem (or has acquired the libio list lock). It does not
address the general issue of async-signal-safety of fork;
multi-threaded processes are not covered, and some glibc
subsystems have fork handlers which are not async-signal-safe.
