From 9f7378a9d6ced1784e08d3e21a9ddb769523baf2 Mon Sep 17 00:00:00 2001 From: Dean Jenkins Date: Wed, 14 Oct 2015 12:18:47 +0200 Subject: [PATCH] Bluetooth: l2cap_disconnection_req priority over shutdown There is a L2CAP protocol race between the local peer and the remote peer demanding disconnection of the L2CAP link. When L2CAP ERTM is used, l2cap_sock_shutdown() can be called from userland to disconnect L2CAP. However, there can be a delay introduced by waiting for ACKs. During this waiting period, the remote peer may have sent a Disconnection Request. Therefore, recheck the shutdown status of the socket after waiting for ACKs because there is no need to do further processing if the connection has gone. Signed-off-by: Dean Jenkins Signed-off-by: Harish Jenny K N Signed-off-by: Marcel Holtmann --- net/bluetooth/l2cap_sock.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index d06fb54..1bb5515 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1129,9 +1129,17 @@ static int l2cap_sock_shutdown(struct socket *sock, int how) if (chan->mode == L2CAP_MODE_ERTM && chan->unacked_frames > 0 && - chan->state == BT_CONNECTED) + chan->state == BT_CONNECTED) { err = __l2cap_wait_ack(sk, chan); + /* After waiting for ACKs, check whether shutdown + * has already been actioned to close the L2CAP + * link such as by l2cap_disconnection_req(). + */ + if (sk->sk_shutdown) + goto has_shutdown; + } + sk->sk_shutdown = SHUTDOWN_MASK; release_sock(sk); @@ -1162,6 +1170,7 @@ static int l2cap_sock_shutdown(struct socket *sock, int how) err = bt_sock_wait_state(sk, BT_CLOSED, sk->sk_lingertime); +has_shutdown: l2cap_chan_put(chan); sock_put(sk); -- 2.7.4