Lazy tlsdesc relocation is racy because the static tls optimization and
tlsdesc management operations are done without holding the dlopen lock.
This similar to the commit b7cf203b5c
for aarch64, but it fixes a different race: bug 27137.
Another issue is that ld auditing ignores DT_BIND_NOW and thus tries to
relocate tlsdesc lazily, but that does not work in a BIND_NOW module
due to missing DT_TLSDESC_PLT. Unconditionally relocating tlsdesc at
load time fixes this bug 27721 too.
map is not valid to access here because it can be freed by a concurrent
dlclose: during tls access (via __tls_get_addr) _dl_update_slotinfo is
called without holding dlopen locks. So don't check the modid of map.
The map == 0 and map != 0 code paths can be shared (avoiding the dtv
resize in case of map == 0 is just an optimization: larger dtv than
necessary would be fine too).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Since
commit a509eb117f
Avoid late dlopen failure due to scope, TLS slotinfo updates [BZ #25112]
the generation counter update is not needed in the failure path.
That commit ensures allocation in _dl_add_to_slotinfo happens before
the demarcation point in dlopen (it is called twice, first time is for
allocation only where dlopen can still be reverted on failure, then
second time actual dtv updates are done which then cannot fail).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The test dlopens a large number of modules with TLS, they are reused
from an existing test.
The test relies on the reuse of slotinfo entries after dlclose, without
bug 27135 fixed this needs a failing dlopen. With a slotinfo list that
has non-monotone increasing generation counters, bug 27136 can trigger.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The max modid is a valid index in the dtv, it should not be skipped.
The bug is observable if the last module has modid == 64 and its
generation is same or less than the max generation of the previous
modules. Then dtv[0].counter implies dtv[64] is initialized but
it isn't. Fixes bug 27136.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The value of PR_TAGGED_ADDR_ENABLE was incorrect in the installed
headers and the prctl command macros were missing that are needed
for it to be useful (PR_SET_TAGGED_ADDR_CTRL). Linux headers have
the definitions since 5.4 so it's widely available, we don't need
to repeat these definitions. The remaining definitions are from
Linux 5.10.
To build glibc with --enable-memory-tagging, Linux 5.4 headers and
binutils 2.33.1 or newer is needed.
Reviewed-by: DJ Delorie <dj@redhat.com>
Since Linux 4.13, kernel limits the maximum command line arguments
length to 6 MiB [1]. Normally the limit is still quarter of the maximum
stack size but if that limit exceeds 6 MiB it's clamped down.
glibc's __sysconf implementation for Linux platform is not aware of
this limitation and for stack sizes of over 24 MiB it returns higher
ARG_MAX than Linux will actually accept. This can be verified by
executing the following application on Linux 4.13 or newer:
#include <stdio.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <unistd.h>
int main(void) {
const struct rlimit rlim = { 40 * 1024 * 1024,
40 * 1024 * 1024 };
if (setrlimit(RLIMIT_STACK, &rlim) < 0) {
perror("setrlimit: RLIMIT_STACK");
return 1;
}
printf("ARG_MAX : %8ld\n", sysconf(_SC_ARG_MAX));
printf("63 * 100 KiB: %8ld\n", 63L * 100 * 1024);
printf("6 MiB : %8ld\n", 6L * 1024 * 1024);
char str[100 * 1024], *argv[64], *envp[1];
memset(&str, 'A', sizeof str);
str[sizeof str - 1] = '\0';
for (size_t i = 0; i < sizeof argv / sizeof *argv - 1; ++i) {
argv[i] = str;
}
argv[sizeof argv / sizeof *argv - 1] = envp[0] = 0;
execve("/bin/true", argv, envp);
perror("execve");
return 1;
}
On affected systems the program will report ARG_MAX as 10 MiB but
despite that executing /bin/true with a bit over 6 MiB of command line
arguments will fail with E2BIG error. Expected result is that ARG_MAX
is reported as 6 MiB.
Update the __sysconf function to clamp ARG_MAX value to 6 MiB if it
would otherwise exceed it. This resolves bug #25305 which was market
WONTFIX as suggested solution was to cap ARG_MAX at 128 KiB.
As an aside and point of comparison, bionic (a libc implementation for
Android systems) decided to resolve this issue by always returning 128
KiB ignoring any potential xargs regressions [2].
On older kernels this results in returning overly conservative value
but that's a safer option than being aggressive and returning invalid
value on recent systems. It's also worth noting that at this point
all supported Linux releases have the 6 MiB barrier so only someone
running an unsupported kernel version would get incorrectly truncated
result.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
[1] See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=da029c11e6b12f321f36dac8771e833b65cec962
[2] See baed51ee3a
POSIX states for syslog [1]:
"Values of the priority argument are formed by OR'ing together a
severity-level value and an optional facility value. If no
facility value is specified, the current default facility value is
used."
So the patch fixes an existing violation of the openlog interface contract
where it is ignoring the facility argument when the value is zero
It allows the use LOG_KERN by calling openlog prior syslog usage.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/syslog.html
Cover key corner cases (e.g., whether errno is set) that are well
settled in glibc, fix some examples to avoid integer overflow, and
update some other dated examples (code needed for K&R C, e.g.).
* manual/charset.texi (Non-reentrant String Conversion):
* manual/filesys.texi (Symbolic Links):
* manual/memory.texi (Allocating Cleared Space):
* manual/socket.texi (Host Names):
* manual/string.texi (Concatenating Strings):
* manual/users.texi (Setting Groups):
Use reallocarray instead of realloc, to avoid integer overflow issues.
* manual/filesys.texi (Scanning Directory Content):
* manual/memory.texi (The GNU Allocator, Hooks for Malloc):
* manual/tunables.texi:
Use code font for 'malloc' instead of roman font.
(Symbolic Links): Don't assume readlink return value fits in 'int'.
* manual/memory.texi (Memory Allocation and C, Basic Allocation)
(Malloc Examples, Alloca Example):
* manual/stdio.texi (Formatted Output Functions):
* manual/string.texi (Concatenating Strings, Collation Functions):
Omit pointer casts that are needed only in ancient K&R C.
* manual/memory.texi (Basic Allocation):
Say that malloc sets errno on failure.
Say "convert" rather than "cast", since casts are no longer needed.
* manual/memory.texi (Basic Allocation):
* manual/string.texi (Concatenating Strings):
In examples, use C99 declarations after statements for brevity.
* manual/memory.texi (Malloc Examples): Add portability notes for
malloc (0), errno setting, and PTRDIFF_MAX.
(Changing Block Size): Say that realloc (p, 0) acts like
(p ? (free (p), NULL) : malloc (0)).
Add xreallocarray example, since other examples can use it.
Add portability notes for realloc (0, 0), realloc (p, 0),
PTRDIFF_MAX, and improve notes for reallocating to the same size.
(Allocating Cleared Space): Reword now-confusing discussion
about replacement, and xref "Replacing malloc".
* manual/stdio.texi (Formatted Output Functions):
Don't assume message size fits in 'int'.
* manual/string.texi (Concatenating Strings):
Fix undefined behavior involving arithmetic on a freed pointer.
The commit 2433d39b69, which added time64 support to select, changed
the function to use __NR_pselect6 (or __NR_pelect6_time64) on all
architectures. However, on architectures where the symbol was
implemented with __NR_select the kernel normalizes the passed timeout
instead of return EINVAL. For instance, the input timeval
{ 0, 5000000 } is interpreted as { 5, 0 }.
And as indicated by BZ #27651, this semantic seems to be expected
and changing it results in some performance issues (most likely
the program does not check the return code and keeps issuing
select with unormalized tv_usec argument).
To avoid a different semantic depending whether which syscall the
architecture used to issue, select now always normalize the timeout
input. This is a slight change for some ABIs (for instance aarch64).
Checked on x86_64-linux-gnu and i686-linux-gnu.
When parse_tunables tries to erase a tunable marked as SXID_ERASE for
setuid programs, it ends up setting the envvar string iterator
incorrectly, because of which it may parse the next tunable
incorrectly. Given that currently the implementation allows malformed
and unrecognized tunables pass through, it may even allow SXID_ERASE
tunables to go through.
This change revamps the SXID_ERASE implementation so that:
- Only valid tunables are written back to the tunestr string, because
of which children of SXID programs will only inherit a clean list of
identified tunables that are not SXID_ERASE.
- Unrecognized tunables get scrubbed off from the environment and
subsequently from the child environment.
- This has the side-effect that a tunable that is not identified by
the setxid binary, will not be passed on to a non-setxid child even
if the child could have identified that tunable. This may break
applications that expect this behaviour but expecting such tunables
to cross the SXID boundary is wrong.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Instead of passing GLIBC_TUNABLES via the environment, pass the
environment variable from parent to child. This allows us to test
multiple variables to ensure better coverage.
The test list currently only includes the case that's already being
tested. More tests will be added later.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Add a new function support_capture_subprogram_self_sgid that spawns an
sgid child of the running program with its own image and returns the
exit code of the child process. This functionality is used by at
least three tests in the testsuite at the moment, so it makes sense to
consolidate.
There is also a new function support_subprogram_wait which should
provide simple system() like functionality that does not set up file
actions. This is useful in cases where only the return code of the
spawned subprocess is interesting.
This patch also ports tst-secure-getenv to this new function. A
subsequent patch will port other tests. This also brings an important
change to tst-secure-getenv behaviour. Now instead of succeeding, the
test fails as UNSUPPORTED if it is unable to spawn a setgid child,
which is how it should have been in the first place.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
An incorrect check in __longjmp_chk could fail on valid code causing
FAIL: debug/tst-longjmp_chk2
The original check was
altstack_sp + altstack_size - setjmp_sp > altstack_size
i.e. sp at setjmp was outside of the altstack range. Here we know that
longjmp is called from a signal handler on the altstack (SS_ONSTACK),
and that it jumps in the wrong direction (sp decreases), so the check
wants to ensure the jump goes to another stack.
The check is wrong when altstack_sp == setjmp_sp which can happen
when the altstack is a local buffer in the function that calls setjmp,
so the patch allows == too. This fixes bug 27709.
Note that the generic __longjmp_chk check seems to be different.
(it checks if longjmp was on the altstack but does not check setjmp,
so it would not catch incorrect longjmp use within the signal handler).
With this patch, the maximal known error for tgamma is now reduced to 9 ulps
for dbl-64, for all rounding modes. Since exhaustive testing is not possible
for dbl-64, it might be that there are still cases with an error larger than
9 ulps, but all known cases are fixed (intensive tests were done to find cases
with large errors).
Tested on x86_64 and powerpc (and by Adhemerval Zanella on aarch64, arm,
s390x, sparc, and i686).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The simplification of tunable_set interfaces took care of
signed/unsigned conversions while setting values, but comparison with
bounds ended up being incorrect; comparing TUNABLE_SIZE_T values for
example will fail because SIZE_MAX is seen as -1.
Add comparison helpers that take tunable types into account and use
them to do comparison instead.
The 13th edition of Svenska Akademiens ordlista lists 'W' as a
distinct letter that sorts after 'V'. We adjust the sv_SE locale
(and tests) to match this updated and "reformed" language change.
This harmonizes us with CLDR 1.5.0 (2007) for sv_SE sorting of
the letter 'W'.
No regressions on x86_64, and locale sorting tests all pass.
Co-authored-by: Carlos O'Donell <carlos@redhat.com>
dlopen updates libname_list by writing to lastp->next, but concurrent
reads in _dl_name_match_p were not synchronized when it was called
without holding GL(dl_load_lock), which can happen during lazy symbol
resolution.
This patch fixes the race between _dl_name_match_p reading lastp->next
and add_name_to_object writing to it. This could cause segfault on
targets with weak memory order when lastp->next->name is read, which
was observed on an arm system. Fixes bug 21349.
(Code is from Maninder Singh, comments and description is from Szabolcs
Nagy.)
Co-authored-by: Vaneet Narang <v.narang@samsung.com>
Co-authored-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
DL_UNMAP_IS_SPECIAL and DL_UNMAP were not defined. The definitions are
now copied from arm, since the same is needed on aarch64. The cleanup
of tlsdesc data is handled by the custom _dl_unmap.
Fixes bug 27403.
For j0f/j1f/y0f/y1f, the largest error for all binary32
inputs is reduced to at most 9 ulps for all rounding modes.
The new code is enabled only when there is a cancellation at the very end of
the j0f/j1f/y0f/y1f computation, or for very large inputs, thus should not
give any visible slowdown on average. Two different algorithms are used:
* around the first 64 zeros of j0/j1/y0/y1, approximation polynomials of
degree 3 are used, computed using the Sollya tool (https://www.sollya.org/)
* for large inputs, an asymptotic formula from [1] is used
[1] Fast and Accurate Bessel Function Computation,
John Harrison, Proceedings of Arith 19, 2009.
Inputs yielding the new largest errors are added to auto-libm-test-in,
and ulps are regenerated for various targets (thanks Adhemerval Zanella).
Tested on x86_64 with --disable-multi-arch and on powerpc64le-linux-gnu.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The c59f716993 (accept) and 3ddf9bc185 (connect) added on io/Makefile
instead of socket/Makefile.
Checked on arm-linux-gnueabihf (where without the flags both the
tst-cancelx4 and tst-cancelx5 fails).
config/i386/constraints.md in GCC has
(define_constraint "e"
"32-bit signed integer constant, or a symbolic reference known
to fit that range (for immediate operands in sign-extending x86-64
instructions)."
(match_operand 0 "x86_64_immediate_operand"))
Since movq takes a signed 32-bit immediate or a register source operand,
use "er", instead of "nr"/"ir", constraint for 32-bit signed integer
constant or register on movq.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This fixes missing definition of math functions in libc in a static link
that are no longer built for libm after commit 4898d9712b ("Avoid adding
duplicated symbols into static libraries").
