Commit 22ce97fe authored Oct 17, 2017 by Colin Ian King Committed by David S. Miller Oct 19, 2017

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: 4e8b86c0 ("mqprio: Introduce new hardware offload mode and shaper in mqprio")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent fa31f0c9

net/sched/sch_mqprio.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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));