From 99372c38a948823060e9123ce6ec6bcba43d9387 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Fri, 2 Oct 2020 12:13:34 -0700 Subject: [PATCH] net_sched: check error pointer in tcf_dump_walker() [ Upstream commit 580e4273d7a883ececfefa692c1f96bdbacb99b5 ] Although we take RTNL on dump path, it is possible to skip RTNL on insertion path. So the following race condition is possible: rtnl_lock() // no rtnl lock mutex_lock(&idrinfo->lock); // insert ERR_PTR(-EBUSY) mutex_unlock(&idrinfo->lock); tc_dump_action() rtnl_unlock() So we have to skip those temporary -EBUSY entries on dump path too. Reported-and-tested-by: syzbot+b47bc4f247856fb4d9e1@syzkaller.appspotmail.com Fixes: 0fedc63fadf0 ("net_sched: commit action insertions together") Cc: Vlad Buslov Cc: Jamal Hadi Salim Cc: Jiri Pirko Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sched/act_api.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 17e5cd9ebd89..75132d0ca887 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -231,6 +231,8 @@ static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb, index++; if (index < s_i) continue; + if (IS_ERR(p)) + continue; if (jiffy_since && time_after(jiffy_since,