Merge pull request #2621 from JacobBarthelmeh/SanityChecks

sanity check on "a" input to invmod
2019-12-02 10:57:01 -08:00
parent bfaa970d84 2efa91632e
commit 7e45ae2ec6
2 changed files with 7 additions and 2 deletions
--- a/wolfcrypt/src/integer.c
+++ b/wolfcrypt/src/integer.c
@@ -966,8 +966,8 @@ int wolfcrypt_mp_invmod(mp_int * a, mp_int * b, mp_int * c)
 int mp_invmod (mp_int * a, mp_int * b, mp_int * c)
 #endif
 {
-  /* b cannot be negative */
-  if (b->sign == MP_NEG || mp_iszero(b) == MP_YES) {
+  /* b cannot be negative or zero, and can not divide by 0 (1/a mod b) */
+  if (b->sign == MP_NEG || mp_iszero(b) == MP_YES || mp_iszero(a) == MP_YES) {
    return MP_VAL;
  }