changed types to avoid overflow

Author: czurnieden

bn_mp_ilogb.c

@@ -1,17 +1,7 @@
 #include "tommath_private.h"
 #ifdef BN_MP_ILOGB_C
-/* LibTomMath, multiple-precision integer library -- Tom St Denis
- *
- * LibTomMath is a library that provides multiple-precision
- * integer arithmetic as well as number theoretic functionality.
- *
- * The library was designed directly after the MPI library by
- * Michael Fromberger but has been written from scratch with
- * additional optimizations in place.
- *
- * SPDX-License-Identifier: Unlicense
- */
-
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
 
 /* Compute log_{base}(a) */
 static mp_word s_pow(mp_word base, mp_word exponent)
@@ -68,9 +58,9 @@ static mp_digit s_digit_ilogb(mp_digit base, mp_digit n)
    }
 
    if (bracket_high == N) {
-      ret = (mp_digit) high;
+      ret = high;
    } else {
-      ret = (mp_digit) low;
+      ret = low;
    }
 
    return ret;
@@ -83,7 +73,7 @@ static mp_digit s_digit_ilogb(mp_digit base, mp_digit n)
 int mp_ilogb(mp_int *a, mp_digit base, mp_int *c)
 {
    int err, cmp;
-   mp_digit high, low, mid;
+   unsigned int high, low, mid;
    mp_int bracket_low, bracket_high, bracket_mid, t, bi_base;
    mp_digit tmp;
 
@@ -98,8 +88,8 @@ int mp_ilogb(mp_int *a, mp_digit base, mp_int *c)
    if (base < 2) {
       return MP_VAL;
    } else if (base == 2) {
-      tmp = (mp_digit)mp_count_bits(a) - 1;
-      mp_set(c, tmp);
+      cmp = mp_count_bits(a) - 1;
+      mp_set_int(c, (unsigned long)cmp);
       return err;
    } else if (a->used == 1) {
       tmp = s_digit_ilogb(base, a->dp[0]);
@@ -150,6 +140,11 @@ int mp_ilogb(mp_int *a, mp_digit base, mp_int *c)
 
    while ((high - low) > 1) {
       mid = (high + low) >> 1;
+      /* Difference can be larger then the type behind mp_digit can hold */
+      if ((mid - low) > (unsigned int)(MP_MASK)) {
+         err = MP_VAL;
+         goto LBL_ERR;
+      }
       if ((err = mp_expt_d(&bi_base, (mid - low), &t)) != MP_OKAY) {
          goto LBL_ERR;
       }
@@ -166,17 +161,15 @@ int mp_ilogb(mp_int *a, mp_digit base, mp_int *c)
          mp_exch(&bracket_mid, &bracket_low);
       }
       if (cmp == MP_EQ) {
-         mp_set(c, mid);
+         mp_set_int(c, (unsigned long)mid);
          goto LBL_ERR;
       }
    }
 
    if (mp_cmp(&bracket_high, a) == MP_EQ) {
-      mp_set(c, high);
-      goto LBL_ERR;
+      mp_set_int(c, (unsigned long)high);
    } else {
-      mp_set(c, low);
-      goto LBL_ERR;
+      mp_set_int(c, (unsigned long)low);
    }
 
 LBL_ERR:
@@ -187,6 +180,3 @@ int mp_ilogb(mp_int *a, mp_digit base, mp_int *c)
 
 
 #endif
-/* ref:         $Format:%D$ */
-/* git commit:  $Format:%H$ */
-/* commit time: $Format:%ai$ */

callgraph.txt

@@ -2644,6 +2644,8 @@ BN_MP_ILOGB_C
 |   |   +--->BN_MP_CLEAR_C
 |   +--->BN_MP_CLEAR_C
 +--->BN_MP_COUNT_BITS_C
++--->BN_MP_SET_INT_C
+|   +--->BN_MP_SET_LONG_C
 +--->BN_MP_SET_C
 |   +--->BN_MP_ZERO_C
 +--->BN_MP_CMP_D_C

tommath_class.h

@@ -471,6 +471,7 @@
 #   define BN_MP_RADIX_SIZE_C
 #   define BN_MP_BITCOUNT_C
 #   define BN_MP_COUNT_BITS_C
+#   define BN_MP_SET_INT_C
 #   define BN_MP_SET_C
 #   define BN_MP_CMP_D_C
 #   define BN_MP_ZERO_C