Merge pull request #352 from ejohnstown/fix-fuzz

Fuzzing Fixes

Author: JacobBarthelmeh

src/internal.c

@@ -3533,13 +3533,17 @@ static int DoKexDhGexGroup(WOLFSSH* ssh,
         ret = GetMpint(&generatorSz, &generator, buf, len, &begin);
 
     if (ret == WS_SUCCESS) {
+        if (ssh->handshake->primeGroup)
+            WFREE(ssh->handshake->primeGroup, ssh->ctx->heap, DYNTYPE_MPINT);
         ssh->handshake->primeGroup =
             (byte*)WMALLOC(primeGroupSz, ssh->ctx->heap, DYNTYPE_MPINT);
         if (ssh->handshake->primeGroup == NULL)
             ret = WS_MEMORY_E;
     }
 
     if (ret == WS_SUCCESS) {
+        if (ssh->handshake->generator)
+            WFREE(ssh->handshake->generator, ssh->ctx->heap, DYNTYPE_MPINT);
         ssh->handshake->generator =
             (byte*)WMALLOC(generatorSz, ssh->ctx->heap, DYNTYPE_MPINT);
         if (ssh->handshake->generator == NULL) {

src/misc.c

@@ -130,6 +130,9 @@ STATIC INLINE void CreateMpint(byte* buf, word32* sz, byte* pad)
         WLOG(WS_LOG_ERROR, "Internal argument error with CreateMpint");
     }
 
+    if (*sz == 0)
+        return;
+
     /* check for leading 0's */
     for (i = 0; i < *sz; i++) {
         if (buf[i] != 0x00)