| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.15 060/122] Bluetooth: Fix deadlock in l2cap_conn_del() | Date | Mon, 7 Jul 2014 16:57:02 -0700 |
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3.15-stable review patch. If anyone has any objections, please let me know.
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From: Jukka Taimisto <jtt@codenomicon.com>
commit 7ab56c3a6eccb215034b0cb096e0313441cbf2a4 upstream.
A deadlock occurs when PDU containing invalid SMP opcode is received on Security Manager Channel over LE link and conn->pending_rx_work worker has not run yet.
When LE link is created l2cap_conn_ready() is called and before returning it schedules conn->pending_rx_work worker to hdev->workqueue. Incoming data to SMP fixed channel is handled by l2cap_recv_frame() which calls smp_sig_channel() to handle the SMP PDU. If smp_sig_channel() indicates failure l2cap_conn_del() is called to delete the connection. When deleting the connection, l2cap_conn_del() purges the pending_rx queue and calls flush_work() to wait for the pending_rx_work worker to complete.
Since incoming data is handled by a worker running from the same workqueue as the pending_rx_work is being scheduled on, we will deadlock on waiting for pending_rx_work to complete.
This patch fixes the deadlock by calling cancel_work_sync() instead of flush_work().
Signed-off-by: Jukka Taimisto <jtt@codenomicon.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- net/bluetooth/l2cap_core.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -1657,7 +1657,13 @@ static void l2cap_conn_del(struct hci_co kfree_skb(conn->rx_skb); skb_queue_purge(&conn->pending_rx); - flush_work(&conn->pending_rx_work); + + /* We can not call flush_work(&conn->pending_rx_work) here since we + * might block if we are running on a worker from the same workqueue + * pending_rx_work is waiting on. + */ + if (work_pending(&conn->pending_rx_work)) + cancel_work_sync(&conn->pending_rx_work); l2cap_unregister_all_users(conn);
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