netdev - [Patch net] net_sched: add max len check for TCA

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Message-Id: <20190918232412.16718-1-xiyou.wangcong@gmail.com>
Date:   Wed, 18 Sep 2019 16:24:12 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        syzbot+618aacd49e8c8b8486bd@...kaller.appspotmail.com,
        David Ahern <dsahern@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>
Subject: [Patch net] net_sched: add max len check for TCA_KIND

The TCA_KIND attribute is of NLA_STRING which does not check
the NUL char. KMSAN reported an uninit-value of TCA_KIND which
is likely caused by the lack of NUL.

Change it to NLA_NUL_STRING and add a max len too.

Fixes: 8b4c3cdd9dd8 ("net: sched: Add policy validation for tc attributes")
Reported-and-tested-by: syzbot+618aacd49e8c8b8486bd@...kaller.appspotmail.com
Cc: David Ahern <dsahern@...il.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Jiri Pirko <jiri@...nulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 net/sched/sch_api.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 1047825d9f48..81d58b280612 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1390,7 +1390,8 @@ check_loop_fn(struct Qdisc *q, unsigned long cl, struct qdisc_walker *w)
 }
 
 const struct nla_policy rtm_tca_policy[TCA_MAX + 1] = {
-	[TCA_KIND]		= { .type = NLA_STRING },
+	[TCA_KIND]		= { .type = NLA_NUL_STRING,
+				    .len = IFNAMSIZ - 1 },
 	[TCA_RATE]		= { .type = NLA_BINARY,
 				    .len = sizeof(struct tc_estimator) },
 	[TCA_STAB]		= { .type = NLA_NESTED },
-- 
2.21.0