glibc/malloc/malloc-debug.c

/* Malloc debug DSO.
   Copyright (C) 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/>.  */

#include <atomic.h>
#include <libc-symbols.h>
#include <shlib-compat.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>

/* Support only the glibc allocators.  */
extern void *__libc_malloc (size_t);
extern void __libc_free (void *);
extern void *__libc_realloc (void *, size_t);
extern void *__libc_memalign (size_t, size_t);
extern void *__libc_valloc (size_t);
extern void *__libc_pvalloc (size_t);
extern void *__libc_calloc (size_t, size_t);

#define DEBUG_FN(fn) \
  static __typeof (__libc_ ## fn) __debug_ ## fn

DEBUG_FN(malloc);
DEBUG_FN(free);
DEBUG_FN(realloc);
DEBUG_FN(memalign);
DEBUG_FN(valloc);
DEBUG_FN(pvalloc);
DEBUG_FN(calloc);

extern void (*__free_hook) (void *, const void *);
compat_symbol_reference (libc, __free_hook, __free_hook, GLIBC_2_0);
extern void * (*__malloc_hook) (size_t, const void *);
compat_symbol_reference (libc, __malloc_hook, __malloc_hook, GLIBC_2_0);
extern void * (*__realloc_hook) (void *, size_t, const void *);
compat_symbol_reference (libc, __realloc_hook, __realloc_hook, GLIBC_2_0);
extern void * (*__memalign_hook) (size_t, size_t, const void *);
compat_symbol_reference (libc, __memalign_hook, __memalign_hook, GLIBC_2_0);

static size_t pagesize;

/* The allocator functions.  */

static void *
__debug_malloc (size_t bytes)
{
  void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook);
  if (__builtin_expect (hook != NULL, 0))
    return (*hook)(bytes, RETURN_ADDRESS (0));

  return __libc_malloc (bytes);
}
strong_alias (__debug_malloc, malloc)

static void
__debug_free (void *mem)
{
  void (*hook) (void *, const void *) = atomic_forced_read (__free_hook);
  if (__builtin_expect (hook != NULL, 0))
    {
      (*hook)(mem, RETURN_ADDRESS (0));
      return;
    }
  __libc_free (mem);
}
strong_alias (__debug_free, free)

static void *
__debug_realloc (void *oldmem, size_t bytes)
{
  void *(*hook) (void *, size_t, const void *) =
    atomic_forced_read (__realloc_hook);
  if (__builtin_expect (hook != NULL, 0))
    return (*hook)(oldmem, bytes, RETURN_ADDRESS (0));

  return __libc_realloc (oldmem, bytes);
}
strong_alias (__debug_realloc, realloc)

static void *
_debug_mid_memalign (size_t alignment, size_t bytes, const void *address)
{
  void *(*hook) (size_t, size_t, const void *) =
    atomic_forced_read (__memalign_hook);
  if (__builtin_expect (hook != NULL, 0))
    return (*hook)(alignment, bytes, address);

  return __libc_memalign (alignment, bytes);
}

static void *
__debug_memalign (size_t alignment, size_t bytes)
{
  return _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0));
}
strong_alias (__debug_memalign, memalign)
strong_alias (__debug_memalign, aligned_alloc)

static void *
__debug_pvalloc (size_t bytes)
{
  size_t rounded_bytes;

  if (!pagesize)
    pagesize = sysconf (_SC_PAGESIZE);

  /* ALIGN_UP with overflow check.  */
  if (__glibc_unlikely (__builtin_add_overflow (bytes,
						pagesize - 1,
						&rounded_bytes)))
    {
      errno = ENOMEM;
      return NULL;
    }
  rounded_bytes = rounded_bytes & -(pagesize - 1);

  return _debug_mid_memalign (pagesize, rounded_bytes, RETURN_ADDRESS (0));
}
strong_alias (__debug_pvalloc, pvalloc)

static void *
__debug_valloc (size_t bytes)
{
  if (!pagesize)
    pagesize = sysconf (_SC_PAGESIZE);

  return _debug_mid_memalign (pagesize, bytes, RETURN_ADDRESS (0));
}
strong_alias (__debug_valloc, valloc)

static int
__debug_posix_memalign (void **memptr, size_t alignment, size_t bytes)
{
  /* Test whether the SIZE argument is valid.  It must be a power of
     two multiple of sizeof (void *).  */
  if (alignment % sizeof (void *) != 0
      || !powerof2 (alignment / sizeof (void *))
      || alignment == 0)
    return EINVAL;

  *memptr = _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0));

  if (*memptr == NULL)
    return ENOMEM;

  return 0;
}
strong_alias (__debug_posix_memalign, posix_memalign)

static void *
__debug_calloc (size_t nmemb, size_t size)
{
  void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook);
  if (__builtin_expect (hook != NULL, 0))
    {
      size_t bytes;

      if (__glibc_unlikely (__builtin_mul_overflow (nmemb, size, &bytes)))
	{
	  errno = ENOMEM;
	  return NULL;
	}

      void *mem = (*hook)(bytes, RETURN_ADDRESS (0));

      if (mem != NULL)
	memset (mem, 0, bytes);

      return mem;
    }

  return __libc_calloc (nmemb, size);
}
strong_alias (__debug_calloc, calloc)