From: jsing <jsing@openbsd.org>
Date: Sat, 24 Jun 2023 17:06:54 +0000 (+0000)
Subject: Add conditional around bn_mul_words() call.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=cad21cb54290e13c9f42ce0760638bc908479b2c;p=openbsd

Add conditional around bn_mul_words() call.

At least one of our bn_mul_words() assembly implementation fails to handle
n = 0 correctly... *sigh*
---

diff --git a/lib/libcrypto/bn/bn_sqr.c b/lib/libcrypto/bn/bn_sqr.c
index 56664e2e36b..5ea1bd45b9d 100644
--- a/lib/libcrypto/bn/bn_sqr.c
+++ b/lib/libcrypto/bn/bn_sqr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_sqr.c,v 1.33 2023/06/24 16:19:52 jsing Exp $ */
+/* $OpenBSD: bn_sqr.c,v 1.34 2023/06/24 17:06:54 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -214,7 +214,9 @@ bn_sqr_normal(BN_ULONG *r, int r_len, const BN_ULONG *a, int a_len,
 
 	/* Compute initial product - r[n:1] = a[n:1] * a[0] */
 	n = a_len - 1;
-	rp[n] = bn_mul_words(rp, ap, n, w);
+	if (n > 0) {
+		rp[n] = bn_mul_words(rp, ap, n, w);
+	}
 	rp += 2;
 	n--;