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authorLiping Zhang <zlpnobody@gmail.com>2017-04-17 21:18:56 +0800
committerPablo Neira Ayuso <pablo@netfilter.org>2017-04-24 20:06:28 +0200
commit88be4c09d9008f9ff337cbf48c5d0f06c8f872e7 (patch)
tree58116fa74feaafe98c9abe3d18434cdff177ddd7 /net/netfilter
parent14e567615679a9999ce6bf4f23d6c9e00f03e00e (diff)
netfilter: ctnetlink: fix deadlock due to acquire _expect_lock twice
Currently, ctnetlink_change_conntrack is always protected by _expect_lock, but this will cause a deadlock when deleting the helper from a conntrack, as the _expect_lock will be acquired again by nf_ct_remove_expectations: CPU0 ---- lock(nf_conntrack_expect_lock); lock(nf_conntrack_expect_lock); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by lt-conntrack_gr/12853: #0: (&table[i].mutex){+.+.+.}, at: [<ffffffffa05e2009>] nfnetlink_rcv_msg+0x399/0x6a9 [nfnetlink] #1: (nf_conntrack_expect_lock){+.....}, at: [<ffffffffa05f2c1f>] ctnetlink_new_conntrack+0x17f/0x408 [nf_conntrack_netlink] Call Trace: dump_stack+0x85/0xc2 __lock_acquire+0x1608/0x1680 ? ctnetlink_parse_tuple_proto+0x10f/0x1c0 [nf_conntrack_netlink] lock_acquire+0x100/0x1f0 ? nf_ct_remove_expectations+0x32/0x90 [nf_conntrack] _raw_spin_lock_bh+0x3f/0x50 ? nf_ct_remove_expectations+0x32/0x90 [nf_conntrack] nf_ct_remove_expectations+0x32/0x90 [nf_conntrack] ctnetlink_change_helper+0xc6/0x190 [nf_conntrack_netlink] ctnetlink_new_conntrack+0x1b2/0x408 [nf_conntrack_netlink] nfnetlink_rcv_msg+0x60a/0x6a9 [nfnetlink] ? nfnetlink_rcv_msg+0x1b9/0x6a9 [nfnetlink] ? nfnetlink_bind+0x1a0/0x1a0 [nfnetlink] netlink_rcv_skb+0xa4/0xc0 nfnetlink_rcv+0x87/0x770 [nfnetlink] Since the operations are unrelated to nf_ct_expect, so we can drop the _expect_lock. Also note, after removing the _expect_lock protection, another CPU may invoke nf_conntrack_helper_unregister, so we should use rcu_read_lock to protect __nf_conntrack_helper_find invoked by ctnetlink_change_helper. Fixes: ca7433df3a67 ("netfilter: conntrack: seperate expect locking from nf_conntrack_lock") Signed-off-by: Liping Zhang <zlpnobody@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter')
-rw-r--r--net/netfilter/nf_conntrack_netlink.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 48c184552de0..e5f97777b1f4 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1510,23 +1510,29 @@ static int ctnetlink_change_helper(struct nf_conn *ct,
return 0;
}
+ rcu_read_lock();
helper = __nf_conntrack_helper_find(helpname, nf_ct_l3num(ct),
nf_ct_protonum(ct));
- if (helper == NULL)
+ if (helper == NULL) {
+ rcu_read_unlock();
return -EOPNOTSUPP;
+ }
if (help) {
if (help->helper == helper) {
/* update private helper data if allowed. */
if (helper->from_nlattr)
helper->from_nlattr(helpinfo, ct);
- return 0;
+ err = 0;
} else
- return -EBUSY;
+ err = -EBUSY;
+ } else {
+ /* we cannot set a helper for an existing conntrack */
+ err = -EOPNOTSUPP;
}
- /* we cannot set a helper for an existing conntrack */
- return -EOPNOTSUPP;
+ rcu_read_unlock();
+ return err;
}
static int ctnetlink_change_timeout(struct nf_conn *ct,
@@ -1945,9 +1951,7 @@ 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);
if (err == 0) {
nf_conntrack_eventmask_report((1 << IPCT_REPLY) |
(1 << IPCT_ASSURED) |
@@ -2342,11 +2346,7 @@ ctnetlink_glue_parse(const struct nlattr *attr, struct nf_conn *ct)
if (ret < 0)
return ret;
- spin_lock_bh(&nf_conntrack_expect_lock);
- ret = ctnetlink_glue_parse_ct((const struct nlattr **)cda, ct);
- spin_unlock_bh(&nf_conntrack_expect_lock);
-
- return ret;
+ return ctnetlink_glue_parse_ct((const struct nlattr **)cda, ct);
}
static int ctnetlink_glue_exp_parse(const struct nlattr * const *cda,