From: jsing <jsing@openbsd.org>
Date: Sat, 24 Jun 2023 16:10:23 +0000 (+0000)
Subject: Check for non-zero length rather than a zero value.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=bc591847e51645c65de8e7dd9927cade552c8ff6;p=openbsd

Check for non-zero length rather than a zero value.

This removes a data dependent timing path from BN_sqr().

ok tb@
---

diff --git a/lib/libcrypto/bn/bn_sqr.c b/lib/libcrypto/bn/bn_sqr.c
index 4eab796c906..5f3be22304c 100644
--- a/lib/libcrypto/bn/bn_sqr.c
+++ b/lib/libcrypto/bn/bn_sqr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_sqr.c,v 1.31 2023/06/24 16:01:43 jsing Exp $ */
+/* $OpenBSD: bn_sqr.c,v 1.32 2023/06/24 16:10:23 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -274,7 +274,7 @@ BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
 
 	BN_CTX_start(ctx);
 
-	if (BN_is_zero(a)) {
+	if (a->top < 1) {
 		BN_zero(r);
 		goto done;
 	}