mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-21 12:30:06 +00:00
Remove malloc hooks [BZ #23328]
Make malloc hooks symbols compat-only so that new applications cannot link against them and remove the declarations from the API. Also remove the unused malloc-hooks.h. Finally, mark all symbols in libc_malloc_debug.so as compat so that the library cannot be linked against. Add a note about the deprecation in NEWS. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Siddhesh Poyarekar
parent
0552fd2c7d
commit
1e5a5866cb
10
NEWS
10
NEWS
@ -143,6 +143,16 @@ Deprecated and removed features, and other changes affecting compatibility:
|
||||
that still use these functions will now need to preload libc_malloc_debug.so
|
||||
in their environment using the LD_PRELOAD environment variable.
|
||||
|
||||
* The deprecated memory allocation hooks __malloc_hook, __realloc_hook,
|
||||
__memalign_hook and __free_hook are now removed from the API. Compatibility
|
||||
symbols are present to support legacy programs but new applications can no
|
||||
longer link to these symbols. These hooks no longer have any effect on glibc
|
||||
functionality. The malloc debugging DSO libc_malloc_debug.so currently
|
||||
supports hooks and can be preloaded to get this functionality back for older
|
||||
programs. However this is a transitional measure and may be removed in a
|
||||
future release of the GNU C Library. Users may port away from these hooks by
|
||||
writing and preloading their own malloc interposition library.
|
||||
|
||||
Changes to build and runtime requirements:
|
||||
|
||||
* On Linux, the shm_open, sem_open, and related functions now expect the
|
||||
|
||||
@ -32,12 +32,16 @@ void weak_variable (*__after_morecore_hook) (void) = NULL;
|
||||
compat_symbol (libc, __after_morecore_hook, __after_morecore_hook, GLIBC_2_0);
|
||||
void *(*__morecore)(ptrdiff_t);
|
||||
compat_symbol (libc, __morecore, __morecore, GLIBC_2_0);
|
||||
#endif
|
||||
|
||||
void weak_variable (*__free_hook) (void *, const void *) = NULL;
|
||||
void *weak_variable (*__malloc_hook) (size_t, const void *) = NULL;
|
||||
void *weak_variable (*__realloc_hook) (void *, size_t, const void *) = NULL;
|
||||
void *weak_variable (*__memalign_hook) (size_t, size_t, const void *) = NULL;
|
||||
compat_symbol (libc, __free_hook, __free_hook, GLIBC_2_0);
|
||||
compat_symbol (libc, __malloc_hook, __malloc_hook, GLIBC_2_0);
|
||||
compat_symbol (libc, __realloc_hook, __realloc_hook, GLIBC_2_0);
|
||||
compat_symbol (libc, __memalign_hook, __memalign_hook, GLIBC_2_0);
|
||||
#endif
|
||||
|
||||
/*
|
||||
* Local variables:
|
||||
|
||||
@ -23,6 +23,7 @@
|
||||
#include <unistd.h>
|
||||
#include <sys/param.h>
|
||||
|
||||
#if SHLIB_COMPAT (libc_malloc_debug, GLIBC_2_0, GLIBC_2_34)
|
||||
/* Support only the glibc allocators. */
|
||||
extern void *__libc_malloc (size_t);
|
||||
extern void __libc_free (void *);
|
||||
@ -76,9 +77,11 @@ __malloc_debug_disable (enum malloc_debug_hooks flag)
|
||||
#include "mtrace.c"
|
||||
#include "malloc-check.c"
|
||||
|
||||
#if SHLIB_COMPAT (libc_malloc_debug, GLIBC_2_0, GLIBC_2_24)
|
||||
extern void (*__malloc_initialize_hook) (void);
|
||||
compat_symbol_reference (libc, __malloc_initialize_hook,
|
||||
__malloc_initialize_hook, GLIBC_2_0);
|
||||
#endif
|
||||
|
||||
static void *malloc_hook_ini (size_t, const void *) __THROW;
|
||||
static void *realloc_hook_ini (void *, size_t, const void *) __THROW;
|
||||
@ -115,9 +118,11 @@ generic_hook_ini (void)
|
||||
will not try to optimize it away. */
|
||||
__libc_free (__libc_malloc (0));
|
||||
|
||||
#if SHLIB_COMPAT (libc_malloc_debug, GLIBC_2_0, GLIBC_2_24)
|
||||
void (*hook) (void) = __malloc_initialize_hook;
|
||||
if (hook != NULL)
|
||||
(*hook)();
|
||||
#endif
|
||||
|
||||
debug_initialized = 1;
|
||||
}
|
||||
@ -631,3 +636,34 @@ malloc_set_state (void *msptr)
|
||||
compat_symbol (libc_malloc_debug, malloc_set_state, malloc_set_state,
|
||||
GLIBC_2_0);
|
||||
#endif
|
||||
|
||||
/* Do not allow linking against the library. */
|
||||
compat_symbol (libc_malloc_debug, aligned_alloc, aligned_alloc, GLIBC_2_16);
|
||||
compat_symbol (libc_malloc_debug, calloc, calloc, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, free, free, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, mallinfo2, mallinfo2, GLIBC_2_33);
|
||||
compat_symbol (libc_malloc_debug, mallinfo, mallinfo, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, malloc_info, malloc_info, GLIBC_2_10);
|
||||
compat_symbol (libc_malloc_debug, malloc, malloc, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, malloc_stats, malloc_stats, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, malloc_trim, malloc_trim, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, malloc_usable_size, malloc_usable_size,
|
||||
GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, mallopt, mallopt, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, mcheck_check_all, mcheck_check_all,
|
||||
GLIBC_2_2);
|
||||
compat_symbol (libc_malloc_debug, mcheck, mcheck, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, mcheck_pedantic, mcheck_pedantic, GLIBC_2_2);
|
||||
compat_symbol (libc_malloc_debug, memalign, memalign, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, mprobe, mprobe, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, mtrace, mtrace, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, muntrace, muntrace, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, posix_memalign, posix_memalign, GLIBC_2_2);
|
||||
compat_symbol (libc_malloc_debug, pvalloc, pvalloc, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, realloc, realloc, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, valloc, valloc, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, __free_hook, __free_hook, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, __malloc_hook, __malloc_hook, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, __realloc_hook, __realloc_hook, GLIBC_2_0);
|
||||
compat_symbol (libc_malloc_debug, __memalign_hook, __memalign_hook, GLIBC_2_0);
|
||||
#endif
|
||||
|
||||
@ -1,24 +0,0 @@
|
||||
/* Internal declarations of malloc hooks no longer in the public API.
|
||||
Copyright (C) 2016-2021 Free Software Foundation, Inc.
|
||||
This file is part of the GNU C Library.
|
||||
|
||||
The GNU C Library is free software; you can redistribute it and/or
|
||||
modify it under the terms of the GNU Lesser General Public License as
|
||||
published by the Free Software Foundation; either version 2.1 of the
|
||||
License, or (at your option) any later version.
|
||||
|
||||
The GNU C Library is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||
Lesser General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU Lesser General Public
|
||||
License along with the GNU C Library; see the file COPYING.LIB. If
|
||||
not, see <https://www.gnu.org/licenses/>. */
|
||||
|
||||
#ifndef _MALLOC_HOOKS_H
|
||||
#define _MALLOC_HOOKS_H
|
||||
|
||||
void (*__malloc_initialize_hook) (void);
|
||||
|
||||
#endif /* _MALLOC_HOOKS_H */
|
||||
@ -156,21 +156,5 @@ extern void malloc_stats (void) __THROW;
|
||||
/* Output information about state of allocator to stream FP. */
|
||||
extern int malloc_info (int __options, FILE *__fp) __THROW;
|
||||
|
||||
/* Hooks for debugging and user-defined versions. */
|
||||
extern void (*__MALLOC_HOOK_VOLATILE __free_hook) (void *__ptr,
|
||||
const void *)
|
||||
__MALLOC_DEPRECATED;
|
||||
extern void *(*__MALLOC_HOOK_VOLATILE __malloc_hook)(size_t __size,
|
||||
const void *)
|
||||
__MALLOC_DEPRECATED;
|
||||
extern void *(*__MALLOC_HOOK_VOLATILE __realloc_hook)(void *__ptr,
|
||||
size_t __size,
|
||||
const void *)
|
||||
__MALLOC_DEPRECATED;
|
||||
extern void *(*__MALLOC_HOOK_VOLATILE __memalign_hook)(size_t __alignment,
|
||||
size_t __size,
|
||||
const void *)
|
||||
__MALLOC_DEPRECATED;
|
||||
|
||||
__END_DECLS
|
||||
#endif /* malloc.h */
|
||||
|
||||
@ -328,8 +328,6 @@ any time (or never).
|
||||
* Malloc Tunable Parameters:: Use @code{mallopt} to adjust allocation
|
||||
parameters.
|
||||
* Heap Consistency Checking:: Automatic checking for errors.
|
||||
* Hooks for Malloc:: You can use these hooks for debugging
|
||||
programs that use @code{malloc}.
|
||||
* Statistics of Malloc:: Getting information about how much
|
||||
memory your program is using.
|
||||
* Summary of Malloc:: Summary of @code{malloc} and related functions.
|
||||
@ -1392,170 +1390,6 @@ compatibility. Both @code{MALLOC_CHECK_} and @samp{-lmcheck} should
|
||||
uncover the same bugs - but using @code{MALLOC_CHECK_} you don't need to
|
||||
recompile your application.
|
||||
|
||||
@node Hooks for Malloc
|
||||
@subsubsection Memory Allocation Hooks
|
||||
@cindex allocation hooks, for @code{malloc}
|
||||
|
||||
@Theglibc{} lets you modify the behavior of @code{malloc},
|
||||
@code{realloc}, and @code{free} by specifying appropriate hook
|
||||
functions. You can use these hooks to help you debug programs that use
|
||||
dynamic memory allocation, for example.
|
||||
|
||||
The hook variables are declared in @file{malloc.h}.
|
||||
@pindex malloc.h
|
||||
|
||||
@defvar __malloc_hook
|
||||
@standards{GNU, malloc.h}
|
||||
The value of this variable is a pointer to the function that
|
||||
@code{malloc} uses whenever it is called. You should define this
|
||||
function to look like @code{malloc}; that is, like:
|
||||
|
||||
@smallexample
|
||||
void *@var{function} (size_t @var{size}, const void *@var{caller})
|
||||
@end smallexample
|
||||
|
||||
The value of @var{caller} is the return address found on the stack when
|
||||
the @code{malloc} function was called. This value allows you to trace
|
||||
the memory consumption of the program.
|
||||
@end defvar
|
||||
|
||||
@defvar __realloc_hook
|
||||
@standards{GNU, malloc.h}
|
||||
The value of this variable is a pointer to function that @code{realloc}
|
||||
uses whenever it is called. You should define this function to look
|
||||
like @code{realloc}; that is, like:
|
||||
|
||||
@smallexample
|
||||
void *@var{function} (void *@var{ptr}, size_t @var{size}, const void *@var{caller})
|
||||
@end smallexample
|
||||
|
||||
The value of @var{caller} is the return address found on the stack when
|
||||
the @code{realloc} function was called. This value allows you to trace the
|
||||
memory consumption of the program.
|
||||
@end defvar
|
||||
|
||||
@defvar __free_hook
|
||||
@standards{GNU, malloc.h}
|
||||
The value of this variable is a pointer to function that @code{free}
|
||||
uses whenever it is called. You should define this function to look
|
||||
like @code{free}; that is, like:
|
||||
|
||||
@smallexample
|
||||
void @var{function} (void *@var{ptr}, const void *@var{caller})
|
||||
@end smallexample
|
||||
|
||||
The value of @var{caller} is the return address found on the stack when
|
||||
the @code{free} function was called. This value allows you to trace the
|
||||
memory consumption of the program.
|
||||
@end defvar
|
||||
|
||||
@defvar __memalign_hook
|
||||
@standards{GNU, malloc.h}
|
||||
The value of this variable is a pointer to function that @code{aligned_alloc},
|
||||
@code{memalign}, @code{posix_memalign} and @code{valloc} use whenever they
|
||||
are called. You should define this function to look like @code{aligned_alloc};
|
||||
that is, like:
|
||||
|
||||
@smallexample
|
||||
void *@var{function} (size_t @var{alignment}, size_t @var{size}, const void *@var{caller})
|
||||
@end smallexample
|
||||
|
||||
The value of @var{caller} is the return address found on the stack when
|
||||
the @code{aligned_alloc}, @code{memalign}, @code{posix_memalign} or
|
||||
@code{valloc} functions are called. This value allows you to trace the
|
||||
memory consumption of the program.
|
||||
@end defvar
|
||||
|
||||
You must make sure that the function you install as a hook for one of
|
||||
these functions does not call that function recursively without restoring
|
||||
the old value of the hook first! Otherwise, your program will get stuck
|
||||
in an infinite recursion. Before calling the function recursively, one
|
||||
should make sure to restore all the hooks to their previous value. When
|
||||
coming back from the recursive call, all the hooks should be resaved
|
||||
since a hook might modify itself.
|
||||
|
||||
An issue to look out for is the time at which the hook functions
|
||||
can be safely installed. If the hook functions call the @code{malloc}-related
|
||||
functions recursively, it is necessary that @code{malloc} has already properly
|
||||
initialized itself at the time when @code{__malloc_hook} etc. is
|
||||
assigned to. On the other hand, if the hook functions provide a
|
||||
complete @code{malloc} implementation of their own, it is vital that the hooks
|
||||
are assigned to @emph{before} the very first @code{malloc} call has
|
||||
completed, because otherwise a chunk obtained from the ordinary,
|
||||
un-hooked @code{malloc} may later be handed to @code{__free_hook}, for example.
|
||||
|
||||
Here is an example showing how to use @code{__malloc_hook} and
|
||||
@code{__free_hook} properly. It installs a function that prints out
|
||||
information every time @code{malloc} or @code{free} is called. We just
|
||||
assume here that @code{realloc} and @code{memalign} are not used in our
|
||||
program.
|
||||
|
||||
@smallexample
|
||||
/* Prototypes for __malloc_hook, __free_hook */
|
||||
#include <malloc.h>
|
||||
|
||||
/* Prototypes for our hooks. */
|
||||
static void my_init_hook (void);
|
||||
static void *my_malloc_hook (size_t, const void *);
|
||||
static void my_free_hook (void*, const void *);
|
||||
|
||||
static void
|
||||
my_init (void)
|
||||
@{
|
||||
old_malloc_hook = __malloc_hook;
|
||||
old_free_hook = __free_hook;
|
||||
__malloc_hook = my_malloc_hook;
|
||||
__free_hook = my_free_hook;
|
||||
@}
|
||||
|
||||
static void *
|
||||
my_malloc_hook (size_t size, const void *caller)
|
||||
@{
|
||||
void *result;
|
||||
/* Restore all old hooks */
|
||||
__malloc_hook = old_malloc_hook;
|
||||
__free_hook = old_free_hook;
|
||||
/* Call recursively */
|
||||
result = malloc (size);
|
||||
/* Save underlying hooks */
|
||||
old_malloc_hook = __malloc_hook;
|
||||
old_free_hook = __free_hook;
|
||||
/* @r{@code{printf} might call @code{malloc}, so protect it too.} */
|
||||
printf ("malloc (%u) returns %p\n", (unsigned int) size, result);
|
||||
/* Restore our own hooks */
|
||||
__malloc_hook = my_malloc_hook;
|
||||
__free_hook = my_free_hook;
|
||||
return result;
|
||||
@}
|
||||
|
||||
static void
|
||||
my_free_hook (void *ptr, const void *caller)
|
||||
@{
|
||||
/* Restore all old hooks */
|
||||
__malloc_hook = old_malloc_hook;
|
||||
__free_hook = old_free_hook;
|
||||
/* Call recursively */
|
||||
free (ptr);
|
||||
/* Save underlying hooks */
|
||||
old_malloc_hook = __malloc_hook;
|
||||
old_free_hook = __free_hook;
|
||||
/* @r{@code{printf} might call @code{free}, so protect it too.} */
|
||||
printf ("freed pointer %p\n", ptr);
|
||||
/* Restore our own hooks */
|
||||
__malloc_hook = my_malloc_hook;
|
||||
__free_hook = my_free_hook;
|
||||
@}
|
||||
|
||||
main ()
|
||||
@{
|
||||
my_init ();
|
||||
@dots{}
|
||||
@}
|
||||
@end smallexample
|
||||
|
||||
The @code{mcheck} function (@pxref{Heap Consistency Checking}) works by
|
||||
installing such hooks.
|
||||
|
||||
@c __morecore, __after_morecore_hook are undocumented
|
||||
@c It's not clear whether to document them.
|
||||
|
||||
@ -1690,19 +1524,6 @@ Tell @code{malloc} to perform occasional consistency checks on
|
||||
dynamically allocated memory, and to call @var{abortfn} when an
|
||||
inconsistency is found. @xref{Heap Consistency Checking}.
|
||||
|
||||
@item void *(*__malloc_hook) (size_t @var{size}, const void *@var{caller})
|
||||
A pointer to a function that @code{malloc} uses whenever it is called.
|
||||
|
||||
@item void *(*__realloc_hook) (void *@var{ptr}, size_t @var{size}, const void *@var{caller})
|
||||
A pointer to a function that @code{realloc} uses whenever it is called.
|
||||
|
||||
@item void (*__free_hook) (void *@var{ptr}, const void *@var{caller})
|
||||
A pointer to a function that @code{free} uses whenever it is called.
|
||||
|
||||
@item void (*__memalign_hook) (size_t @var{size}, size_t @var{alignment}, const void *@var{caller})
|
||||
A pointer to a function that @code{aligned_alloc}, @code{memalign},
|
||||
@code{posix_memalign} and @code{valloc} use whenever they are called.
|
||||
|
||||
@item struct mallinfo2 mallinfo2 (void)
|
||||
Return information about the current dynamic memory usage.
|
||||
@xref{Statistics of Malloc}.
|
||||
@ -1737,7 +1558,7 @@ penalties for the program if the debugging mode is not enabled.
|
||||
|
||||
@deftypefun void mtrace (void)
|
||||
@standards{GNU, mcheck.h}
|
||||
@safety{@prelim{}@mtunsafe{@mtsenv{} @mtasurace{:mtrace} @mtasuconst{:malloc_hooks} @mtuinit{}}@asunsafe{@asuinit{} @ascuheap{} @asucorrupt{} @asulock{}}@acunsafe{@acuinit{} @acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
|
||||
@safety{@prelim{}@mtunsafe{@mtsenv{} @mtasurace{:mtrace} @mtuinit{}}@asunsafe{@asuinit{} @ascuheap{} @asucorrupt{} @asulock{}}@acunsafe{@acuinit{} @acucorrupt{} @aculock{} @acsfd{} @acsmem{}}}
|
||||
@c Like the mcheck hooks, these are not designed with thread safety in
|
||||
@c mind, because the hook pointers are temporarily modified without
|
||||
@c regard to other threads, signals or cancellation.
|
||||
@ -1768,10 +1589,10 @@ with the SUID or SGID bit set.
|
||||
|
||||
If the named file is successfully opened, @code{mtrace} installs special
|
||||
handlers for the functions @code{malloc}, @code{realloc}, and
|
||||
@code{free} (@pxref{Hooks for Malloc}). From then on, all uses of these
|
||||
functions are traced and protocolled into the file. There is now of
|
||||
course a speed penalty for all calls to the traced functions so tracing
|
||||
should not be enabled during normal use.
|
||||
@code{free}. From then on, all uses of these functions are traced and
|
||||
protocolled into the file. There is now of course a speed penalty for all
|
||||
calls to the traced functions so tracing should not be enabled during normal
|
||||
use.
|
||||
|
||||
This function is a GNU extension and generally not available on other
|
||||
systems. The prototype can be found in @file{mcheck.h}.
|
||||
@ -1779,7 +1600,7 @@ systems. The prototype can be found in @file{mcheck.h}.
|
||||
|
||||
@deftypefun void muntrace (void)
|
||||
@standards{GNU, mcheck.h}
|
||||
@safety{@prelim{}@mtunsafe{@mtasurace{:mtrace} @mtasuconst{:malloc_hooks} @mtslocale{}}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{} @aculock{} @acsfd{}}}
|
||||
@safety{@prelim{}@mtunsafe{@mtasurace{:mtrace} @mtslocale{}}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{} @aculock{} @acsfd{}}}
|
||||
|
||||
@c muntrace @mtasurace:mtrace @mtslocale @asucorrupt @ascuheap @acucorrupt @acsmem @aculock @acsfd
|
||||
@c fprintf (fputs) dup @mtslocale @asucorrupt @ascuheap @acsmem @aculock @acucorrupt
|
||||
|
||||
Loading…
Reference in New Issue
Block a user