1 /* Standard debugging hooks for `malloc'.
2 Copyright (C) 1990-2013 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Written May 1989 by Mike Haertel.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
20 #ifndef _MALLOC_INTERNAL
21 # define _MALLOC_INTERNAL
30 /* Old hook values. */
31 static void (*old_free_hook) (__ptr_t ptr, const __ptr_t);
32 static __ptr_t (*old_malloc_hook) (size_t size, const __ptr_t);
33 static __ptr_t (*old_memalign_hook) (size_t alignment, size_t size,
35 static __ptr_t (*old_realloc_hook) (__ptr_t ptr, size_t size,
38 /* Function to call when something awful happens. */
39 static void (*abortfunc) (enum mcheck_status);
41 /* Arbitrary magical numbers. */
42 #define MAGICWORD 0xfedabeeb
43 #define MAGICFREE 0xd8675309
44 #define MAGICBYTE ((char) 0xd7)
45 #define MALLOCFLOOD ((char) 0x93)
46 #define FREEFLOOD ((char) 0x95)
50 size_t size; /* Exact size requested by user. */
51 unsigned long int magic; /* Magic number to check header integrity. */
54 __ptr_t block; /* Real block allocated, for memalign. */
55 unsigned long int magic2; /* Extra, keeps us doubleword aligned. */
58 /* This is the beginning of the list of all memory blocks allocated.
59 It is only constructed if the pedantic testing is requested. */
60 static struct hdr *root;
62 static int mcheck_used;
64 /* Nonzero if pedentic checking of all blocks is requested. */
67 #if defined _LIBC || defined STDC_HEADERS || defined USG
71 static void flood (__ptr_t, int, size_t);
73 flood (ptr, val, size)
84 static enum mcheck_status
85 checkhdr (const struct hdr *hdr)
87 enum mcheck_status status;
90 /* Maybe the mcheck used is disabled? This happens when we find
91 an error and report it. */
94 switch (hdr->magic ^ ((uintptr_t) hdr->prev + (uintptr_t) hdr->next))
100 status = MCHECK_FREE;
103 if (((char *) &hdr[1])[hdr->size] != MAGICBYTE)
104 status = MCHECK_TAIL;
105 else if ((hdr->magic2 ^ (uintptr_t) hdr->block) != MAGICWORD)
106 status = MCHECK_HEAD;
111 if (status != MCHECK_OK)
114 (*abortfunc) (status);
121 mcheck_check_all (void)
123 /* Walk through all the active blocks and test whether they were tampered
125 struct hdr *runp = root;
127 /* Temporarily turn off the checks. */
132 (void) checkhdr (runp);
137 /* Turn checks on again. */
141 libc_hidden_def (mcheck_check_all)
145 unlink_blk (struct hdr *ptr)
147 if (ptr->next != NULL)
149 ptr->next->prev = ptr->prev;
150 ptr->next->magic = MAGICWORD ^ ((uintptr_t) ptr->next->prev
151 + (uintptr_t) ptr->next->next);
153 if (ptr->prev != NULL)
155 ptr->prev->next = ptr->next;
156 ptr->prev->magic = MAGICWORD ^ ((uintptr_t) ptr->prev->prev
157 + (uintptr_t) ptr->prev->next);
164 link_blk (struct hdr *hdr)
169 hdr->magic = MAGICWORD ^ (uintptr_t) hdr->next;
171 /* And the next block. */
172 if (hdr->next != NULL)
174 hdr->next->prev = hdr;
175 hdr->next->magic = MAGICWORD ^ ((uintptr_t) hdr
176 + (uintptr_t) hdr->next->next);
180 freehook (__ptr_t ptr, const __ptr_t caller)
186 struct hdr *hdr = ((struct hdr *) ptr) - 1;
188 hdr->magic = MAGICFREE;
189 hdr->magic2 = MAGICFREE;
191 hdr->prev = hdr->next = NULL;
192 flood (ptr, FREEFLOOD, hdr->size);
195 __free_hook = old_free_hook;
196 if (old_free_hook != NULL)
197 (*old_free_hook) (ptr, caller);
200 __free_hook = freehook;
204 mallochook (size_t size, const __ptr_t caller)
211 if (size > ~((size_t) 0) - (sizeof (struct hdr) + 1))
213 __set_errno (ENOMEM);
217 __malloc_hook = old_malloc_hook;
218 if (old_malloc_hook != NULL)
219 hdr = (struct hdr *) (*old_malloc_hook) (sizeof (struct hdr) + size + 1,
222 hdr = (struct hdr *) malloc (sizeof (struct hdr) + size + 1);
223 __malloc_hook = mallochook;
230 hdr->magic2 = (uintptr_t) hdr ^ MAGICWORD;
231 ((char *) &hdr[1])[size] = MAGICBYTE;
232 flood ((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
233 return (__ptr_t) (hdr + 1);
237 memalignhook (size_t alignment, size_t size,
238 const __ptr_t caller)
247 slop = (sizeof *hdr + alignment - 1) & -alignment;
249 if (size > ~((size_t) 0) - (slop + 1))
251 __set_errno (ENOMEM);
255 __memalign_hook = old_memalign_hook;
256 if (old_memalign_hook != NULL)
257 block = (*old_memalign_hook) (alignment, slop + size + 1, caller);
259 block = memalign (alignment, slop + size + 1);
260 __memalign_hook = memalignhook;
264 hdr = ((struct hdr *) (block + slop)) - 1;
268 hdr->block = (__ptr_t) block;
269 hdr->magic2 = (uintptr_t) block ^ MAGICWORD;
270 ((char *) &hdr[1])[size] = MAGICBYTE;
271 flood ((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
272 return (__ptr_t) (hdr + 1);
276 reallochook (__ptr_t ptr, size_t size, const __ptr_t caller)
280 freehook (ptr, caller);
290 if (size > ~((size_t) 0) - (sizeof (struct hdr) + 1))
292 __set_errno (ENOMEM);
298 hdr = ((struct hdr *) ptr) - 1;
304 flood ((char *) ptr + size, FREEFLOOD, osize - size);
311 __free_hook = old_free_hook;
312 __malloc_hook = old_malloc_hook;
313 __memalign_hook = old_memalign_hook;
314 __realloc_hook = old_realloc_hook;
315 if (old_realloc_hook != NULL)
316 hdr = (struct hdr *) (*old_realloc_hook) ((__ptr_t) hdr,
317 sizeof (struct hdr) + size + 1,
320 hdr = (struct hdr *) realloc ((__ptr_t) hdr,
321 sizeof (struct hdr) + size + 1);
322 __free_hook = freehook;
323 __malloc_hook = mallochook;
324 __memalign_hook = memalignhook;
325 __realloc_hook = reallochook;
332 hdr->magic2 = (uintptr_t) hdr ^ MAGICWORD;
333 ((char *) &hdr[1])[size] = MAGICBYTE;
335 flood ((char *) (hdr + 1) + osize, MALLOCFLOOD, size - osize);
336 return (__ptr_t) (hdr + 1);
339 __attribute__ ((noreturn))
341 mabort (enum mcheck_status status)
347 msg = _("memory is consistent, library is buggy\n");
350 msg = _("memory clobbered before allocated block\n");
353 msg = _("memory clobbered past end of allocated block\n");
356 msg = _("block freed twice\n");
359 msg = _("bogus mcheck_status, library is buggy\n");
365 fprintf (stderr, "mcheck: %s", msg);
371 /* Memory barrier so that GCC does not optimize out the argument. */
372 #define malloc_opt_barrier(x) \
373 ({ __typeof (x) __x = x; __asm ("" : "+m" (__x)); __x; })
377 void (*func) (enum mcheck_status);
379 abortfunc = (func != NULL) ? func : &mabort;
381 /* These hooks may not be safely inserted if malloc is already in use. */
382 if (__malloc_initialized <= 0 && !mcheck_used)
384 /* We call malloc() once here to ensure it is initialized. */
385 void *p = malloc (0);
386 /* GCC might optimize out the malloc/free pair without a barrier. */
387 p = malloc_opt_barrier (p);
390 old_free_hook = __free_hook;
391 __free_hook = freehook;
392 old_malloc_hook = __malloc_hook;
393 __malloc_hook = mallochook;
394 old_memalign_hook = __memalign_hook;
395 __memalign_hook = memalignhook;
396 old_realloc_hook = __realloc_hook;
397 __realloc_hook = reallochook;
401 return mcheck_used ? 0 : -1;
404 libc_hidden_def (mcheck)
408 mcheck_pedantic (func)
409 void (*func) (enum mcheck_status);
411 int res = mcheck (func);
420 return mcheck_used ? checkhdr (((struct hdr *) ptr) - 1) : MCHECK_DISABLED;