Commit 9dd115d6 authored by Nick Mathewson's avatar Nick Mathewson 🤹
Browse files

Another 10363 instance: this one in tor_memmem fallback code

parent 092ac26e

changes/bug10363

+3 −0
Original line number Diff line number Diff line
@@ -3,4 +3,7 @@ 
      that could, under unlucky circumstances, have led to a pointer

      overflow. Fixes bug #10363; bugfixes on 0.2.0.10-alpha and

      0.2.3.6-alpha. Reported by "bobnomnom".

    - Fix another possibly undefined pointer operations in tor_memmem

      fallback implementation. Another case of bug #10363; bugfix on

      0.1.1.1-alpha.

src/common/compat.c

+14 −6
Original line number Diff line number Diff line
@@ -498,21 +498,29 @@ tor_memmem(const void *_haystack, size_t hlen, 
#else

  /* This isn't as fast as the GLIBC implementation, but it doesn't need to

   * be. */

  const char *p, *end;

  const char *p, *last_possible_start;

  const char *haystack = (const char*)_haystack;

  const char *needle = (const char*)_needle;

  char first;

  tor_assert(nlen);



  if (nlen > hlen)

    return NULL;



  p = haystack;

  end = haystack + hlen;

  /* Last position at which the needle could start. */

  last_possible_start = haystack + hlen - nlen;

  first = *(const char*)needle;

  while ((p = memchr(p, first, end-p))) {

    if (p+nlen > end)

      return NULL;

  while ((p = memchr(p, first, last_possible_start + 1 - p))) {

    if (fast_memeq(p, needle, nlen))

      return p;

    ++p;

    if (++p > last_possible_start) {

      /* This comparison shouldn't be necessary, since if p was previously

       * equal to last_possible_start, the next memchr call would be

       * "memchr(p, first, 0)", which will return NULL. But it clarifies the

       * logic. */

      return NULL;

    }

  }

  return NULL;

#endif

src/test/test_util.c

+4 −0
Original line number Diff line number Diff line
@@ -1045,6 +1045,10 @@ test_util_strmisc(void) 
    test_assert(!tor_memmem(haystack, 4, "cde", 3));

    haystack = "ababcad";

    test_eq_ptr(tor_memmem(haystack, 7, "abc", 3), haystack + 2);

    test_eq_ptr(tor_memmem(haystack, 7, "ad", 2), haystack + 5);

    test_eq_ptr(tor_memmem(haystack, 7, "cad", 3), haystack + 4);

    test_assert(!tor_memmem(haystack, 7, "dadad", 5));

    test_assert(!tor_memmem(haystack, 7, "abcdefghij", 10));

    /* memstr */

    test_eq_ptr(tor_memstr(haystack, 7, "abc"), haystack + 2);

    test_eq_ptr(tor_memstr(haystack, 7, "cad"), haystack + 4);