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mqprio: fix potential null pointer dereference on opt

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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: 4e8b86c062 ("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>
This commit is contained in:
Colin Ian King 2017-10-17 16:01:30 +01:00 committed by David S. Miller
parent fa31f0c98d
commit 22ce97fe49
1 changed files with 2 additions and 1 deletions
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3
net/sched/sch_mqprio.c
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@ -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));