From 55833a8de70589a5000044b6291e190f5a3826ae Mon Sep 17 00:00:00 2001
From: Mansour Ahmadi <m.ahmadi@northeastern.edu>
Date: Tue, 11 Dec 2018 15:48:08 -0500
Subject: [PATCH] add missing check for BN_mod_inverse

Fixes #7650

Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7876)
---
 crypto/rsa/rsa_x931g.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/crypto/rsa/rsa_x931g.c b/crypto/rsa/rsa_x931g.c
index bc03875f3b..160177721c 100644
--- a/crypto/rsa/rsa_x931g.c
+++ b/crypto/rsa/rsa_x931g.c
@@ -128,6 +128,8 @@ int RSA_X931_derive_ex(RSA *rsa, BIGNUM *p1, BIGNUM *p2, BIGNUM *q1,
 
     /* calculate inverse of q mod p */
     rsa->iqmp = BN_mod_inverse(NULL, rsa->q, rsa->p, ctx2);
+    if (rsa->iqmp == NULL)
+        goto err;
 
     ret = 1;
  err:
-- 
2.25.1