From 460b360104d51552a57f39e54b2589c9fd7fa0b3 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Thu, 27 Sep 2018 13:42:19 -0700 Subject: net_sched: fix a crash in tc_new_tfilter() When tcf_block_find() fails, it already rollbacks the qdisc refcnt, so its caller doesn't need to clean up this again. Avoid calling qdisc_put() again by resetting qdisc to NULL for callers. Reported-by: syzbot+37b8770e6d5a8220a039@syzkaller.appspotmail.com Fixes: e368fdb61d8e ("net: sched: use Qdisc rcu API instead of relying on rtnl lock") Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- net/sched/cls_api.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 3de47e99b788..d670d3066ebd 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -717,8 +717,10 @@ static struct tcf_block *tcf_block_find(struct net *net, struct Qdisc **q, errout_rcu: rcu_read_unlock(); errout_qdisc: - if (*q) + if (*q) { qdisc_put(*q); + *q = NULL; + } return ERR_PTR(err); } -- cgit v1.2.3