path: root/net/dccp/ipv4.c
diff options
authorEric Dumazet <edumazet@google.com>2016-02-18 05:39:18 -0800
committerDavid S. Miller <davem@davemloft.net>2016-02-18 11:35:51 -0500
commit7716682cc58e305e22207d5bb315f26af6b1e243 (patch)
treebd3b7c897a192192bf0312cca7f4cd0e5f39da5d /net/dccp/ipv4.c
parentroute: check and remove route cache when we get route (diff)
tcp/dccp: fix another race at listener dismantle
Ilya reported following lockdep splat: kernel: ========================= kernel: [ BUG: held lock freed! ] kernel: 4.5.0-rc1-ceph-00026-g5e0a311 #1 Not tainted kernel: ------------------------- kernel: swapper/5/0 is freeing memory ffff880035c9d200-ffff880035c9dbff, with a lock still held there! kernel: (&(&queue->rskq_lock)->rlock){+.-...}, at: [<ffffffff816f6a88>] inet_csk_reqsk_queue_add+0x28/0xa0 kernel: 4 locks held by swapper/5/0: kernel: #0: (rcu_read_lock){......}, at: [<ffffffff8169ef6b>] netif_receive_skb_internal+0x4b/0x1f0 kernel: #1: (rcu_read_lock){......}, at: [<ffffffff816e977f>] ip_local_deliver_finish+0x3f/0x380 kernel: #2: (slock-AF_INET){+.-...}, at: [<ffffffff81685ffb>] sk_clone_lock+0x19b/0x440 kernel: #3: (&(&queue->rskq_lock)->rlock){+.-...}, at: [<ffffffff816f6a88>] inet_csk_reqsk_queue_add+0x28/0xa0 To properly fix this issue, inet_csk_reqsk_queue_add() needs to return to its callers if the child as been queued into accept queue. We also need to make sure listener is still there before calling sk->sk_data_ready(), by holding a reference on it, since the reference carried by the child can disappear as soon as the child is put on accept queue. Reported-by: Ilya Dryomov <idryomov@gmail.com> Fixes: ebb516af60e1 ("tcp/dccp: fix race at listener dismantle phase") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp/ipv4.c')
1 files changed, 7 insertions, 7 deletions
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 5684e14932bd..902d606324a0 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -824,26 +824,26 @@ lookup:
if (sk->sk_state == DCCP_NEW_SYN_RECV) {
struct request_sock *req = inet_reqsk(sk);
- struct sock *nsk = NULL;
+ struct sock *nsk;
sk = req->rsk_listener;
- if (likely(sk->sk_state == DCCP_LISTEN)) {
- nsk = dccp_check_req(sk, skb, req);
- } else {
+ if (unlikely(sk->sk_state != DCCP_LISTEN)) {
inet_csk_reqsk_queue_drop_and_put(sk, req);
goto lookup;
+ sock_hold(sk);
+ nsk = dccp_check_req(sk, skb, req);
if (!nsk) {
- goto discard_it;
+ goto discard_and_relse;
if (nsk == sk) {
- sock_hold(sk);
} else if (dccp_child_process(sk, nsk, skb)) {
dccp_v4_ctl_send_reset(sk, skb);
- goto discard_it;
+ goto discard_and_relse;
} else {
+ sock_put(sk);
return 0;