git.openwrt.org Git - openwrt/staging/ansuel.git/blob

   1 From c3edc06d1e1360f3570db9155d6b318ae0d0f0f7 Mon Sep 17 00:00:00 2001
   2 From: Rich Felker <dalias@aerifal.cx>
   3 Date: Thu, 6 Oct 2016 18:34:58 -0400
   4 Subject: fix missing integer overflow checks in regexec buffer size
   5  computations
   6
   7 most of the possible overflows were already ruled out in practice by
   8 regcomp having already succeeded performing larger allocations.
   9 however at least the num_states*num_tags multiplication can clearly
  10 overflow in practice. for safety, check them all, and use the proper
  11 type, size_t, rather than int.
  12
  13 also improve comments, use calloc in place of malloc+memset, and
  14 remove bogus casts.
  15 ---
  16  src/regex/regexec.c | 23 ++++++++++++++++++-----
  17  1 file changed, 18 insertions(+), 5 deletions(-)
  18
  19 diff --git a/src/regex/regexec.c b/src/regex/regexec.c
  20 index 16c5d0a..dd52319 100644
  21 --- a/src/regex/regexec.c
  22 +++ b/src/regex/regexec.c
  23 @@ -34,6 +34,7 @@
  24  #include <wchar.h>
  25  #include <wctype.h>
  26  #include <limits.h>
  27 +#include <stdint.h>
  28
  29  #include <regex.h>
  30
  31 @@ -206,11 +207,24 @@ tre_tnfa_run_parallel(const tre_tnfa_t *tnfa, const void *string,
  32
  33    /* Allocate memory for temporary data required for matching. This needs to
  34       be done for every matching operation to be thread safe.  This allocates
  35 -     everything in a single large block from the stack frame using alloca()
  36 -     or with malloc() if alloca is unavailable. */
  37 +     everything in a single large block with calloc(). */
  38    {
  39 -    int tbytes, rbytes, pbytes, xbytes, total_bytes;
  40 +    size_t tbytes, rbytes, pbytes, xbytes, total_bytes;
  41      char *tmp_buf;
  42 +
  43 +    /* Ensure that tbytes and xbytes*num_states cannot overflow, and that
  44 +     * they don't contribute more than 1/8 of SIZE_MAX to total_bytes. */
  45 +    if (num_tags > SIZE_MAX/(8 * sizeof(int) * tnfa->num_states))
  46 +      goto error_exit;
  47 +
  48 +    /* Likewise check rbytes. */
  49 +    if (tnfa->num_states+1 > SIZE_MAX/(8 * sizeof(*reach_next)))
  50 +      goto error_exit;
  51 +
  52 +    /* Likewise check pbytes. */
  53 +    if (tnfa->num_states > SIZE_MAX/(8 * sizeof(*reach_pos)))
  54 +      goto error_exit;
  55 +
  56      /* Compute the length of the block we need. */
  57      tbytes = sizeof(*tmp_tags) * num_tags;
  58      rbytes = sizeof(*reach_next) * (tnfa->num_states + 1);
  59 @@ -221,10 +235,9 @@ tre_tnfa_run_parallel(const tre_tnfa_t *tnfa, const void *string,
  60        + (rbytes + xbytes * tnfa->num_states) * 2 + tbytes + pbytes;
  61
  62      /* Allocate the memory. */
  63 -    buf = xmalloc((unsigned)total_bytes);
  64 +    buf = calloc(total_bytes, 1);
  65      if (buf == NULL)
  66        return REG_ESPACE;
  67 -    memset(buf, 0, (size_t)total_bytes);
  68
  69      /* Get the various pointers within tmp_buf (properly aligned). */
  70      tmp_tags = (void *)buf;
  71 --
  72 cgit v0.11.2