Re: memmem issues

[Bruno Haible]

Paul Eggert wrote:
> OK, I installed this patch.
> 
> 2007-12-29  Paul Eggert  <address@hidden>
> 
>       * lib/memmem.c (knuth_morris_pratt): Check for size_t overflow
>       when multiplying M by sizeof (size_t).

Thanks. Let me generalize it, as follows.


2007-12-30  Bruno Haible  <address@hidden>

        * lib/malloca.h (nmalloca): New macro.
        * lib/c-strcasestr.c (knuth_morris_pratt): Use it.
        * lib/c-strstr.c (knuth_morris_pratt): Likewise.
        * lib/mbscasestr.c (knuth_morris_pratt_unibyte,
        knuth_morris_pratt_multibyte): Likewise.
        * lib/mbsstr.c (knuth_morris_pratt_unibyte,
        knuth_morris_pratt_multibyte): Likewise.
        * lib/memmem.c (knuth_morris_pratt): Likewise.
        * lib/strcasestr.c (knuth_morris_pratt): Likewise.

*** lib/malloca.h.orig  2007-12-30 16:44:24.000000000 +0100
--- lib/malloca.h       2007-12-30 16:21:32.000000000 +0100
***************
*** 70,78 ****
  # define freea free
  #endif
  
! /* Maybe we should also define a variant
!     nmalloca (size_t n, size_t s) - behaves like malloca (n * s)
!    If this would be useful in your application. please speak up.  */
  
  
  #ifdef __cplusplus
--- 70,88 ----
  # define freea free
  #endif
  
! /* nmalloca(N,S) is an overflow-safe variant of malloca (N * S).
!    It allocates an array of N objects, each with S bytes of memory,
!    on the stack.  S must be positive and N must be nonnegative.
!    The array must be freed using freea() before the function returns.  */
! #if 1
! /* Cf. the definition of xalloc_oversized.  */
! # define nmalloca(n, s) \
!     ((n) > (size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) \
!      ? NULL \
!      : malloca ((n) * (s)))
! #else
! extern void * nmalloca (size_t n, size_t s);
! #endif
  
  
  #ifdef __cplusplus
*** lib/c-strcasestr.c.orig     2007-12-30 16:44:24.000000000 +0100
--- lib/c-strcasestr.c  2007-12-30 16:37:08.000000000 +0100
***************
*** 37,43 ****
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) malloca (m * sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
--- 37,43 ----
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) nmalloca (m, sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
*** lib/c-strstr.c.orig 2007-12-30 16:44:24.000000000 +0100
--- lib/c-strstr.c      2007-12-30 16:37:22.000000000 +0100
***************
*** 36,42 ****
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) malloca (m * sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
--- 36,42 ----
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) nmalloca (m, sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
*** lib/mbscasestr.c.orig       2007-12-30 16:44:24.000000000 +0100
--- lib/mbscasestr.c    2007-12-30 16:37:58.000000000 +0100
***************
*** 42,48 ****
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) malloca (m * sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
--- 42,48 ----
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) nmalloca (m, sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
***************
*** 164,170 ****
    size_t *table;
  
    /* Allocate room for needle_mbchars and the table.  */
!   char *memory = (char *) malloca (m * (sizeof (mbchar_t) + sizeof (size_t)));
    if (memory == NULL)
      return false;
    needle_mbchars = (mbchar_t *) memory;
--- 164,170 ----
    size_t *table;
  
    /* Allocate room for needle_mbchars and the table.  */
!   char *memory = (char *) nmalloca (m, sizeof (mbchar_t) + sizeof (size_t));
    if (memory == NULL)
      return false;
    needle_mbchars = (mbchar_t *) memory;
*** lib/mbsstr.c.orig   2007-12-30 16:44:24.000000000 +0100
--- lib/mbsstr.c        2007-12-30 16:39:36.000000000 +0100
***************
*** 39,45 ****
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) malloca (m * sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
--- 39,45 ----
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) nmalloca (m, sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
***************
*** 160,166 ****
    size_t *table;
  
    /* Allocate room for needle_mbchars and the table.  */
!   char *memory = (char *) malloca (m * (sizeof (mbchar_t) + sizeof (size_t)));
    if (memory == NULL)
      return false;
    needle_mbchars = (mbchar_t *) memory;
--- 160,166 ----
    size_t *table;
  
    /* Allocate room for needle_mbchars and the table.  */
!   char *memory = (char *) nmalloca (m, sizeof (mbchar_t) + sizeof (size_t));
    if (memory == NULL)
      return false;
    needle_mbchars = (mbchar_t *) memory;
*** lib/memmem.c.orig   2007-12-30 16:44:24.000000000 +0100
--- lib/memmem.c        2007-12-30 16:38:54.000000000 +0100
***************
*** 39,48 ****
                      const char **resultp)
  {
    /* Allocate the table.  */
!   size_t *table;
!   if ((size_t) -1 / sizeof (size_t) < m)
!     return false;
!   table = (size_t *) malloca (m * sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
--- 39,45 ----
                      const char **resultp)
  {
    /* Allocate the table.  */
!   size_t *table = (size_t *) nmalloca (m, sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
*** lib/strcasestr.c.orig       2007-12-30 16:44:24.000000000 +0100
--- lib/strcasestr.c    2007-12-30 16:39:12.000000000 +0100
***************
*** 39,45 ****
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) malloca (m * sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.
--- 39,45 ----
    size_t m = strlen (needle);
  
    /* Allocate the table.  */
!   size_t *table = (size_t *) nmalloca (m, sizeof (size_t));
    if (table == NULL)
      return false;
    /* Fill the table.