netdev - [iproute PATCH v3 6/6] lib/libnetlink: Don't pass NULL parameter to memcpy()

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Date:   Thu, 24 Aug 2017 11:41:31 +0200
From:   Phil Sutter <phil@....cc>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     netdev@...r.kernel.org
Subject: [iproute PATCH v3 6/6] 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@....cc>
---
 lib/libnetlink.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 874e660be7eb4..fbe719ee10449 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -871,7 +871,8 @@ 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;
 }
@@ -958,7 +959,8 @@ 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;
 }
-- 
2.13.1