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 56664e2..5ea1bd4 100644 (file)
--- 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--;