From: Phil Sutter <phil@nwl.cc>
Date: Thu, 24 Aug 2017 09:46:32 +0000 (+0200)
Subject: tc/q_netem: Don't dereference possibly NULL pointer
X-Git-Tag: v4.13.0~34
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a754de3ccd937500940c6fcd0ad043855f56862d;p=thirdparty%2Fiproute2.git

tc/q_netem: Don't dereference possibly NULL pointer

Assuming 'opt' might be NULL, move the call to RTA_PAYLOAD to after the
check since it dereferences its parameter.

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

diff --git a/tc/q_netem.c b/tc/q_netem.c
index 0975ae111..5a9e74741 100644
--- a/tc/q_netem.c
+++ b/tc/q_netem.c
@@ -538,7 +538,7 @@ static int netem_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
 	int *ecn = NULL;
 	struct tc_netem_qopt qopt;
 	const struct tc_netem_rate *rate = NULL;
-	int len = RTA_PAYLOAD(opt) - sizeof(qopt);
+	int len;
 	__u64 rate64 = 0;
 
 	SPRINT_BUF(b1);
@@ -546,6 +546,7 @@ static int netem_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
 	if (opt == NULL)
 		return 0;
 
+	len = RTA_PAYLOAD(opt) - sizeof(qopt);
 	if (len < 0) {
 		fprintf(stderr, "options size error\n");
 		return -1;