From: Phil Sutter <phil@nwl.cc>
Date: Thu, 24 Aug 2017 09:41:31 +0000 (+0200)
Subject: lib/libnetlink: Don't pass NULL parameter to memcpy()
X-Git-Tag: v4.13.0~17
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=893deac4c43b57ae49f736ec050724b6de181062;p=thirdparty%2Fiproute2.git

lib/libnetlink: Don't pass NULL parameter to memcpy()

Both addattr_l() and rta_addattr_l() may be called with NULL data
pointer and 0 alen parameters. Avoid calling memcpy() in that case.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---

diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 00c853779..be7ac8658 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -870,7 +870,8 @@ int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
 	rta = NLMSG_TAIL(n);
 	rta->rta_type = type;
 	rta->rta_len = len;
-	memcpy(RTA_DATA(rta), data, alen);
+	if (alen)
+		memcpy(RTA_DATA(rta), data, alen);
 	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 	return 0;
 }
@@ -957,7 +958,8 @@ int rta_addattr_l(struct rtattr *rta, int maxlen, int type,
 	subrta = (struct rtattr *)(((char *)rta) + RTA_ALIGN(rta->rta_len));
 	subrta->rta_type = type;
 	subrta->rta_len = len;
-	memcpy(RTA_DATA(subrta), data, alen);
+	if (alen)
+		memcpy(RTA_DATA(subrta), data, alen);
 	rta->rta_len = NLMSG_ALIGN(rta->rta_len) + RTA_ALIGN(len);
 	return 0;
 }