From 22ce97fe49b5522e0f97b7c2282ed71a1abd7410 Mon Sep 17 00:00:00 2001 From: Colin Ian King Date: Tue, 17 Oct 2017 16:01:30 +0100 Subject: mqprio: fix potential null pointer dereference on opt The pointer opt has a null check however before for this check opt is dereferenced when len is initialized, hence we potentially have a null pointer deference on opt. Avoid this by checking for a null opt before dereferencing it. Detected by CoverityScan, CID#1458234 ("Dereference before null check") Fixes: 4e8b86c06269 ("mqprio: Introduce new hardware offload mode and shaper in mqprio") Signed-off-by: Colin Ian King Signed-off-by: David S. Miller --- net/sched/sch_mqprio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/sched/sch_mqprio.c') diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c index cae91b4b08a6..51c2b289c69b 100644 --- a/net/sched/sch_mqprio.c +++ b/net/sched/sch_mqprio.c @@ -142,7 +142,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt) struct nlattr *tb[TCA_MQPRIO_MAX + 1]; struct nlattr *attr; int rem; - int len = nla_len(opt) - NLA_ALIGN(sizeof(*qopt)); + int len; BUILD_BUG_ON(TC_MAX_QUEUE != TC_QOPT_MAX_QUEUE); BUILD_BUG_ON(TC_BITMASK != TC_QOPT_BITMASK); @@ -164,6 +164,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt) if (mqprio_parse_opt(dev, qopt)) return -EINVAL; + len = nla_len(opt) - NLA_ALIGN(sizeof(*qopt)); if (len > 0) { err = parse_attr(tb, TCA_MQPRIO_MAX, opt, mqprio_policy, sizeof(*qopt)); -- cgit v1.2.3