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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 <vladbu@mellanox.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Cong Wang 2020-10-02 12:13:34 -07:00 committed by Greg Kroah-Hartman
parent 5b1de8e15f
commit 99372c38a9
1 changed files with 2 additions and 0 deletions
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2
net/sched/act_api.c
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@ -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,