3.15-stable review patch. If anyone has any objections, please let me know.
------------------ From: Jukka Taimisto <[email protected]> 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 <[email protected]> Signed-off-by: Marcel Holtmann <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
