initialize values used by unsigned bin

Author: rlm2002

wolfcrypt/src/sp_int.c

@@ -18066,6 +18066,7 @@ int sp_read_unsigned_bin(sp_int* a, const byte* in, word32 inSz)
         /* Load full digits at a time from in. */
         int i;
         int j = 0;
+        int k;
 
         a->used = (sp_size_t)((inSz + SP_WORD_SIZEOF - 1) / SP_WORD_SIZEOF);
 
@@ -18077,6 +18078,9 @@ int sp_read_unsigned_bin(sp_int* a, const byte* in, word32 inSz)
             a->dp[j++] = *(sp_int_digit*)(in + i - (SP_WORD_SIZEOF - 1));
         }
     #else
+        for (k = 0; k < (int)a->used; k++) {
+            a->dp[k] = 0;
+        }
         /* Construct digit from required number of bytes. */
         for (i = (int)(inSz-1); i >= SP_WORD_SIZEOF - 1; i -= SP_WORD_SIZEOF) {
             a->dp[j]  = ((sp_int_digit)in[i - 0] <<  0)