[PATCH AUTOSEL 5.2 27/63] net_sched: add max len check for TCA_KIND

From: Cong Wang <redacted>

[ Upstream commit 62794fc4fbf52f2209dc094ea255eaef760e7d01 ]

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@syzkaller.appspotmail.com
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <redacted>
Reviewed-by: David Ahern <redacted>
Acked-by: Jiri Pirko <redacted>
Signed-off-by: Jakub Kicinski <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 04faee7ccbce6..dac9f2887694d 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 },

-- 
2.20.1