Hi Pablo,
2017-04-09 5:16 GMT+08:00 Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>:
> On Sat, Apr 01, 2017 at 10:14:24PM +0800, Liping Zhang wrote:
>> @@ -1960,9 +1955,7 @@ static int ctnetlink_new_conntrack(struct net *net, struct sock *ctnl,
>> err = -EEXIST;
>> ct = nf_ct_tuplehash_to_ctrack(h);
>> if (!(nlh->nlmsg_flags & NLM_F_EXCL)) {
>> - spin_lock_bh(&nf_conntrack_expect_lock);
>> err = ctnetlink_change_conntrack(ct, cda);
>> - spin_unlock_bh(&nf_conntrack_expect_lock);
>
> We used to have a central spinlock here.
>
> spin_lock_bh(&nf_conntrack_lock);
>
> that was removed time ago, so this go converted to use
> nf_conntrack_expect_lock.
This patch should add:
Fixes: ca7433df3a67 ("netfilter: conntrack: seperate expect locking
from nf_conntrack_lock")
Commit ca7433df3a67 add spin_lock_bh(&nf_conntrack_expect_lock) in
nf_ct_remove_expectations, but we also lock the _expect_lock before calling
ctnetlink_change_conntrack, so dead lock will happen:
spin_lock_bh(&nf_conntrack_expect_lock):
->err = ctnetlink_change_conntrack(ct, cda)
-->ctnetlink_change_helper
--->if (!strcmp(helpname, "")) nf_ct_remove_expectations()
---->spin_lock_bh(&nf_conntrack_expect_lock); //lock _expect_lock
again, dead lock!
Since ctnetlink_change_conntrack is unrelated to nf_conntrack_expect_lock,
so remove it can fix this issue.
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