1 files changed, 406 insertions, 0 deletions
diff --git a/malloc/mcheck-impl.c b/malloc/mcheck-impl.c
new file mode 100644
index 0000000000..8857e6b179
--- /dev/null
+++ b/malloc/mcheck-impl.c
@@ -0,0 +1,406 @@
+/* mcheck debugging hooks for malloc.
+   Copyright (C) 1990-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Written May 1989 by Mike Haertel.
+
+   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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <malloc-internal.h>
+#include <mcheck.h>
+#include <libintl.h>
+#include <stdint.h>
+#include <stdio.h>
+
+/* Arbitrary magical numbers.  */
+#define MAGICWORD       0xfedabeeb
+#define MAGICFREE       0xd8675309
+#define MAGICBYTE       ((char) 0xd7)
+#define MALLOCFLOOD     ((char) 0x93)
+#define FREEFLOOD       ((char) 0x95)
+
+/* Function to call when something awful happens.  */
+static void (*abortfunc) (enum mcheck_status);
+
+struct hdr
+{
+  size_t size;                  /* Exact size requested by user.  */
+  unsigned long int magic;      /* Magic number to check header integrity.  */
+  struct hdr *prev;
+  struct hdr *next;
+  void *block;                  /* Real block allocated, for memalign.  */
+  unsigned long int magic2;     /* Extra, keeps us doubleword aligned.  */
+} __attribute__ ((aligned (MALLOC_ALIGNMENT)));
+
+/* This is the beginning of the list of all memory blocks allocated.
+   It is only constructed if the pedantic testing is requested.  */
+static struct hdr *root;
+
+/* Nonzero if pedentic checking of all blocks is requested.  */
+static bool pedantic;
+
+#if defined _LIBC || defined STDC_HEADERS || defined USG
+# include <string.h>
+# define flood memset
+#else
+static void flood (void *, int, size_t);
+static void
+flood (void *ptr, int val, size_t size)
+{
+  char *cp = ptr;
+  while (size--)
+    *cp++ = val;
+}
+#endif
+
+static enum mcheck_status
+checkhdr (const struct hdr *hdr)
+{
+  enum mcheck_status status;
+  bool mcheck_used = __is_malloc_debug_enabled (MALLOC_MCHECK_HOOK);
+
+  if (!mcheck_used)
+    /* Maybe the mcheck used is disabled?  This happens when we find
+       an error and report it.  */
+    return MCHECK_OK;
+
+  switch (hdr->magic ^ ((uintptr_t) hdr->prev + (uintptr_t) hdr->next))
+    {
+    default:
+      status = MCHECK_HEAD;
+      break;
+    case MAGICFREE:
+      status = MCHECK_FREE;
+      break;
+    case MAGICWORD:
+      if (((char *) &hdr[1])[hdr->size] != MAGICBYTE)
+	status = MCHECK_TAIL;
+      else if ((hdr->magic2 ^ (uintptr_t) hdr->block) != MAGICWORD)
+	status = MCHECK_HEAD;
+      else
+	status = MCHECK_OK;
+      break;
+    }
+  if (status != MCHECK_OK)
+    {
+      mcheck_used = 0;
+      (*abortfunc) (status);
+      mcheck_used = 1;
+    }
+  return status;
+}
+
+static enum mcheck_status
+__mcheck_checkptr (const void *ptr)
+{
+  if (!__is_malloc_debug_enabled (MALLOC_MCHECK_HOOK))
+      return MCHECK_DISABLED;
+
+  if (ptr != NULL)
+    return checkhdr (((struct hdr *) ptr) - 1);
+
+  /* Walk through all the active blocks and test whether they were tampered
+     with.  */
+  struct hdr *runp = root;
+
+  /* Temporarily turn off the checks.  */
+  pedantic = false;
+
+  while (runp != NULL)
+    {
+      (void) checkhdr (runp);
+
+      runp = runp->next;
+    }
+
+  /* Turn checks on again.  */
+  pedantic = true;
+
+  return MCHECK_OK;
+}
+
+static void
+unlink_blk (struct hdr *ptr)
+{
+  if (ptr->next != NULL)
+    {
+      ptr->next->prev = ptr->prev;
+      ptr->next->magic = MAGICWORD ^ ((uintptr_t) ptr->next->prev
+                                      + (uintptr_t) ptr->next->next);
+    }
+  if (ptr->prev != NULL)
+    {
+      ptr->prev->next = ptr->next;
+      ptr->prev->magic = MAGICWORD ^ ((uintptr_t) ptr->prev->prev
+                                      + (uintptr_t) ptr->prev->next);
+    }
+  else
+    root = ptr->next;
+}
+
+static void
+link_blk (struct hdr *hdr)
+{
+  hdr->prev = NULL;
+  hdr->next = root;
+  root = hdr;
+  hdr->magic = MAGICWORD ^ (uintptr_t) hdr->next;
+
+  /* And the next block.  */
+  if (hdr->next != NULL)
+    {
+      hdr->next->prev = hdr;
+      hdr->next->magic = MAGICWORD ^ ((uintptr_t) hdr
+                                      + (uintptr_t) hdr->next->next);
+    }
+}
+
+static void *
+free_mcheck (void *ptr)
+{
+  if (pedantic)
+    __mcheck_checkptr (NULL);
+  if (ptr)
+    {
+      struct hdr *hdr = ((struct hdr *) ptr) - 1;
+      checkhdr (hdr);
+      hdr->magic = MAGICFREE;
+      hdr->magic2 = MAGICFREE;
+      unlink_blk (hdr);
+      hdr->prev = hdr->next = NULL;
+      flood (ptr, FREEFLOOD, hdr->size);
+      ptr = hdr->block;
+    }
+  return ptr;
+}
+
+static bool
+malloc_mcheck_before (size_t *sizep, void **victimp)
+{
+  size_t size = *sizep;
+
+  if (pedantic)
+    __mcheck_checkptr (NULL);
+
+  if (size > ~((size_t) 0) - (sizeof (struct hdr) + 1))
+    {
+      __set_errno (ENOMEM);
+      *victimp = NULL;
+      return true;
+    }
+
+  *sizep = sizeof (struct hdr) + size + 1;
+  return false;
+}
+
+static void *
+malloc_mcheck_after (void *mem, size_t size)
+{
+  struct hdr *hdr = mem;
+
+  if (hdr == NULL)
+    return NULL;
+
+  hdr->size = size;
+  link_blk (hdr);
+  hdr->block = hdr;
+  hdr->magic2 = (uintptr_t) hdr ^ MAGICWORD;
+  ((char *) &hdr[1])[size] = MAGICBYTE;
+  flood ((void *) (hdr + 1), MALLOCFLOOD, size);
+  return (void *) (hdr + 1);
+}
+
+static bool
+memalign_mcheck_before (size_t alignment, size_t *sizep, void **victimp)
+{
+  struct hdr *hdr;
+  size_t slop, size = *sizep;
+
+  /* Punt to malloc to avoid double headers.  */
+  if (alignment <= MALLOC_ALIGNMENT)
+    {
+      *victimp = __debug_malloc (size);
+      return true;
+    }
+
+  if (pedantic)
+    __mcheck_checkptr (NULL);
+
+  slop = (sizeof *hdr + alignment - 1) & - alignment;
+
+  if (size > ~((size_t) 0) - (slop + 1))
+    {
+      __set_errno (ENOMEM);
+      *victimp = NULL;
+      return true;
+    }
+
+  *sizep = slop + size + 1;
+  return false;
+}
+
+static void *
+memalign_mcheck_after (void *block, size_t alignment, size_t size)
+{
+  if (block == NULL)
+    return NULL;
+
+  /* This was served by __debug_malloc, so return as is.  */
+  if (alignment <= MALLOC_ALIGNMENT)
+    return block;
+
+  size_t slop = (sizeof (struct hdr) + alignment - 1) & - alignment;
+  struct hdr *hdr = ((struct hdr *) (block + slop)) - 1;
+
+  hdr->size = size;
+  link_blk (hdr);
+  hdr->block = (void *) block;
+  hdr->magic2 = (uintptr_t) block ^ MAGICWORD;
+  ((char *) &hdr[1])[size] = MAGICBYTE;
+  flood ((void *) (hdr + 1), MALLOCFLOOD, size);
+  return (void *) (hdr + 1);
+}
+
+static bool
+realloc_mcheck_before (void **ptrp, size_t *sizep, size_t *oldsize,
+		       void **victimp)
+{
+  size_t size = *sizep;
+  void *ptr = *ptrp;
+
+  if (ptr == NULL)
+    {
+      *victimp = __debug_malloc (size);
+      *oldsize = 0;
+      return true;
+    }
+
+  if (size == 0)
+    {
+      __debug_free (ptr);
+      *victimp = NULL;
+      return true;
+    }
+
+  if (size > ~((size_t) 0) - (sizeof (struct hdr) + 1))
+    {
+      __set_errno (ENOMEM);
+      *victimp = NULL;
+      *oldsize = 0;
+      return true;
+    }
+
+  if (pedantic)
+    __mcheck_checkptr (NULL);
+
+  struct hdr *hdr;
+  size_t osize;
+
+  /* Update the oldptr for glibc realloc.  */
+  *ptrp = hdr = ((struct hdr *) ptr) - 1;
+
+  osize = hdr->size;
+
+  checkhdr (hdr);
+  unlink_blk (hdr);
+  if (size < osize)
+    flood ((char *) ptr + size, FREEFLOOD, osize - size);
+
+  *oldsize = osize;
+  *sizep = sizeof (struct hdr) + size + 1;
+  return false;
+}
+
+static void *
+realloc_mcheck_after (void *ptr, void *oldptr, size_t size, size_t osize)
+{
+  struct hdr *hdr = ptr;
+
+  if (hdr == NULL)
+    return NULL;
+
+  /* Malloc already added the header so don't tamper with it.  */
+  if (oldptr == NULL)
+    return ptr;
+
+  hdr->size = size;
+  link_blk (hdr);
+  hdr->block = hdr;
+  hdr->magic2 = (uintptr_t) hdr ^ MAGICWORD;
+  ((char *) &hdr[1])[size] = MAGICBYTE;
+  if (size > osize)
+    flood ((char *) (hdr + 1) + osize, MALLOCFLOOD, size - osize);
+  return (void *) (hdr + 1);
+}
+
+__attribute__ ((noreturn))
+static void
+mabort (enum mcheck_status status)
+{
+  const char *msg;
+  switch (status)
+    {
+    case MCHECK_OK:
+      msg = _ ("memory is consistent, library is buggy\n");
+      break;
+    case MCHECK_HEAD:
+      msg = _ ("memory clobbered before allocated block\n");
+      break;
+    case MCHECK_TAIL:
+      msg = _ ("memory clobbered past end of allocated block\n");
+      break;
+    case MCHECK_FREE:
+      msg = _ ("block freed twice\n");
+      break;
+    default:
+      msg = _ ("bogus mcheck_status, library is buggy\n");
+      break;
+    }
+#ifdef _LIBC
+  __libc_fatal (msg);
+#else
+  fprintf (stderr, "mcheck: %s", msg);
+  fflush (stderr);
+  abort ();
+#endif
+}
+
+/* Memory barrier so that GCC does not optimize out the argument.  */
+#define malloc_opt_barrier(x) \
+  ({ __typeof (x) __x = x; __asm ("" : "+m" (__x)); __x; })
+
+static int
+__mcheck_initialize (void (*func) (enum mcheck_status), bool in_pedantic)
+{
+  abortfunc = (func != NULL) ? func : &mabort;
+
+  switch (debug_initialized)
+    {
+    case -1:
+      /* Called before the first malloc was called.  */
+      __debug_free (__debug_malloc (0));
+      /* FALLTHROUGH */
+    case 0:
+      /* Called through the initializer hook.  */
+      __malloc_debug_enable (MALLOC_MCHECK_HOOK);
+      break;
+    case 1:
+    default:
+      /* Malloc was already called.  Fail.  */
+      return -1;
+    }
+
+  pedantic = in_pedantic;
+  return 0;
+}