From e363f310b8962ee4bb09788e47fa94a8a0b1366d Mon Sep 17 00:00:00 2001
From: claudio <claudio@openbsd.org>
Date: Fri, 28 Jan 2022 10:41:44 +0000
Subject: [PATCH] Only memcpy() into imsg->data if datalen is not 0. Passing a
 NULL pointer to memcpy() is UB no matter if len is 0. Reported by fouzhe on
 openbgpd-portable github page. OK tb@

---
 lib/libutil/imsg.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/libutil/imsg.c b/lib/libutil/imsg.c
index c0ff22978e0..b381b1edd47 100644
--- a/lib/libutil/imsg.c
+++ b/lib/libutil/imsg.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: imsg.c,v 1.16 2017/12/14 09:27:44 kettenis Exp $	*/
+/*	$OpenBSD: imsg.c,v 1.17 2022/01/28 10:41:44 claudio Exp $	*/
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -150,7 +150,8 @@ imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
 	else
 		imsg->fd = -1;
 
-	memcpy(imsg->data, ibuf->r.rptr, datalen);
+	if (datalen != 0)
+		memcpy(imsg->data, ibuf->r.rptr, datalen);
 
 	if (imsg->hdr.len < av) {
 		left = av - imsg->hdr.len;
-- 
2.20.1