From 3a7ad4f03b62da6b9e2e5e30e1cba5ab7e36e7e9 Mon Sep 17 00:00:00 2001
From: Sean Parkinson <sean@wolfssl.com>
Date: Wed, 19 Aug 2020 08:50:27 +1000
Subject: [PATCH] Check the error return from fp_mod in fp_gcd

Error can occur when using small stack and memory allocation fails.
---
 wolfcrypt/src/tfm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/wolfcrypt/src/tfm.c b/wolfcrypt/src/tfm.c
index bf128174e..8c0a98866 100644
--- a/wolfcrypt/src/tfm.c
+++ b/wolfcrypt/src/tfm.c
@@ -5157,7 +5157,10 @@ int fp_gcd(fp_int *a, fp_int *b, fp_int *c)
 
    fp_init(r);
    while (fp_iszero(v) == FP_NO) {
-      fp_mod(u, v, r);
+      int err = fp_mod(u, v, r);
+      if (err != MP_OKAY) {
+        return err;
+      }
       fp_copy(v, u);
       fp_copy(r, v);
    }