Add check for BN_sub return value

CID 24839

ok jsing@ millert@ tb@

1 files changed, 3 insertions, 2 deletions

diff --git a/src/lib/libcrypto/rsa/rsa_eay.c b/src/lib/libcrypto/rsa/rsa_eay.c
index a45cad0d0a..0f8c324dcc 100644
--- a/src/lib/libcrypto/rsa/rsa_eay.c
+++ b/src/lib/libcrypto/rsa/rsa_eay.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: rsa_eay.c,v 1.53 2022/01/07 09:55:32 tb Exp $ */
+/* $OpenBSD: rsa_eay.c,v 1.54 2022/01/20 11:10:11 inoguchi Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -447,7 +447,8 @@ RSA_eay_private_encrypt(int flen, const unsigned char *from, unsigned char *to,
                         goto err;
 
         if (padding == RSA_X931_PADDING) {
-                BN_sub(f, rsa->n, ret);
+                if (!BN_sub(f, rsa->n, ret))
+                        goto err;
                 if (BN_cmp(ret, f) > 0)
                         res = f;
                 else