From: Colin Ian King <colin.king@canonical.com>
Date: Tue, 17 Oct 2017 16:01:30 +0100
Subject: mqprio: fix potential null pointer dereference on opt
Patch-mainline: v4.15-rc1
Git-commit: 22ce97fe49b5522e0f97b7c2282ed71a1abd7410
References: bsc#1109837
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 <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/sched/sch_mqprio.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- 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 *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
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));