From 38940dfd04fe962674726534b4e88593400cfc1c Mon Sep 17 00:00:00 2001
From: djm <djm@openbsd.org>
Date: Mon, 12 Jan 2015 15:18:07 +0000
Subject: [PATCH] apparently memcpy(x, NULL, 0) is undefined behaviour
 according to C99 (cf. sections 7.21.1 and 7.1.4), so check skip memcpy calls
 when length==0; ok markus@

---
 usr.bin/ssh/sshbuf-getput-basic.c  | 19 ++++++++++++-------
 usr.bin/ssh/sshbuf-getput-crypto.c |  5 +++--
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/usr.bin/ssh/sshbuf-getput-basic.c b/usr.bin/ssh/sshbuf-getput-basic.c
index 8c9e9c5175a..bc2e2f9eb7b 100644
--- a/usr.bin/ssh/sshbuf-getput-basic.c
+++ b/usr.bin/ssh/sshbuf-getput-basic.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sshbuf-getput-basic.c,v 1.2 2014/12/04 01:49:59 djm Exp $	*/
+/*	$OpenBSD: sshbuf-getput-basic.c,v 1.3 2015/01/12 15:18:07 djm Exp $	*/
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -32,7 +32,7 @@ sshbuf_get(struct sshbuf *buf, void *v, size_t len)
 
 	if ((r = sshbuf_consume(buf, len)) < 0)
 		return r;
-	if (v != NULL)
+	if (v != NULL && len != 0)
 		memcpy(v, p, len);
 	return 0;
 }
@@ -107,7 +107,8 @@ sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp)
 			SSHBUF_DBG(("SSH_ERR_ALLOC_FAIL"));
 			return SSH_ERR_ALLOC_FAIL;
 		}
-		memcpy(*valp, val, len);
+		if (len != 0)
+			memcpy(*valp, val, len);
 		(*valp)[len] = '\0';
 	}
 	if (lenp != NULL)
@@ -198,7 +199,8 @@ sshbuf_get_cstring(struct sshbuf *buf, char **valp, size_t *lenp)
 			SSHBUF_DBG(("SSH_ERR_ALLOC_FAIL"));
 			return SSH_ERR_ALLOC_FAIL;
 		}
-		memcpy(*valp, p, len);
+		if (len != 0)
+			memcpy(*valp, p, len);
 		(*valp)[len] = '\0';
 	}
 	if (lenp != NULL)
@@ -234,7 +236,8 @@ sshbuf_put(struct sshbuf *buf, const void *v, size_t len)
 
 	if ((r = sshbuf_reserve(buf, len, &p)) < 0)
 		return r;
-	memcpy(p, v, len);
+	if (len != 0)
+		memcpy(p, v, len);
 	return 0;
 }
 
@@ -350,7 +353,8 @@ sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len)
 	if ((r = sshbuf_reserve(buf, len + 4, &d)) < 0)
 		return r;
 	POKE_U32(d, len);
-	memcpy(d + 4, v, len);
+	if (len != 0)
+		memcpy(d + 4, v, len);
 	return 0;
 }
 
@@ -414,6 +418,7 @@ sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len)
 	POKE_U32(d, len + prepend);
 	if (prepend)
 		d[4] = 0;
-	memcpy(d + 4 + prepend, s, len);
+	if (len != 0)
+		memcpy(d + 4 + prepend, s, len);
 	return 0;
 }
diff --git a/usr.bin/ssh/sshbuf-getput-crypto.c b/usr.bin/ssh/sshbuf-getput-crypto.c
index 79951afda17..f086cae06eb 100644
--- a/usr.bin/ssh/sshbuf-getput-crypto.c
+++ b/usr.bin/ssh/sshbuf-getput-crypto.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sshbuf-getput-crypto.c,v 1.2 2014/06/18 15:42:09 naddy Exp $	*/
+/*	$OpenBSD: sshbuf-getput-crypto.c,v 1.3 2015/01/12 15:18:07 djm Exp $	*/
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -189,7 +189,8 @@ sshbuf_put_bignum1(struct sshbuf *buf, const BIGNUM *v)
 		return r;
 	}
 	POKE_U16(dp, len_bits);
-	memcpy(dp + 2, d, len_bytes);
+	if (len_bytes != 0)
+		memcpy(dp + 2, d, len_bytes);
 	bzero(d, sizeof(d));
 	return 0;
 }
-- 
2.20.1