kc3-lang/libtommath/mp_grow.c

• Show log

  Commit

• Hash : 08d281c4
  Author :
  Date : 2019-12-05T00:48:25
  

  introduce MP_MAX_DIGIT_COUNT to prevent overflow

Download

• mp_grow.c

• #include "tommath_private.h"
  #ifdef MP_GROW_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* grow as required */
  mp_err mp_grow(mp_int *a, int size)
  {
     /* if the alloc size is smaller alloc more ram */
     if (a->alloc < size) {
        mp_digit *dp;
  
        if (size > MP_MAX_DIGIT_COUNT) {
           return MP_MEM;
        }
  
        /* reallocate the array a->dp
         *
         * We store the return in a temporary variable
         * in case the operation failed we don't want
         * to overwrite the dp member of a.
         */
        dp = (mp_digit *) MP_REALLOC(a->dp,
                                     (size_t)a->alloc * sizeof(mp_digit),
                                     (size_t)size * sizeof(mp_digit));
        if (dp == NULL) {
           /* reallocation failed but "a" is still valid [can be freed] */
           return MP_MEM;
        }
  
        /* reallocation succeeded so set a->dp */
        a->dp = dp;
  
        /* zero excess digits */
        s_mp_zero_digs(a->dp + a->alloc, size - a->alloc);
        a->alloc = size;
     }
     return MP_OKAY;
  }
  #endif
  

Download