From: Runyu Xiao Date: Wed, 17 Jun 2026 15:36:13 +0000 (+0800) Subject: Bluetooth: L2CAP: cancel pending_rx_work before taking conn->lock X-Git-Tag: v7.2-rc3~29^2~13^2~15 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2641a9e0a1dd4af2e21995470a21d55dd35e5203;p=thirdparty%2Fkernel%2Flinux.git Bluetooth: L2CAP: cancel pending_rx_work before taking conn->lock l2cap_conn_del() takes conn->lock and then calls cancel_work_sync() for pending_rx_work. process_pending_rx() takes the same mutex, so teardown can deadlock against the worker it is flushing. This issue was found by our static analysis tool and then manually reviewed against the current tree. The grounded PoC kept the l2cap_conn_ready() -> queue_work(..., &conn->pending_rx_work) submit path, the l2cap_conn_del() -> cancel_work_sync(&conn->pending_rx_work) teardown path, and the process_pending_rx() -> mutex_lock(&conn->lock) worker edge. Lockdep reported: WARNING: possible circular locking dependency detected process_pending_rx+0x21/0x2a [vuln_msv] l2cap_conn_del.constprop.0+0x3f/0x4e [vuln_msv] *** DEADLOCK *** Cancel pending_rx_work before taking conn->lock, matching the existing lock-before-drain ordering used for the two delayed works in the same teardown path. The pending_rx queue is still purged after the work has been cancelled and conn->lock has been acquired. Fixes: 7ab56c3a6ecc ("Bluetooth: Fix deadlock in l2cap_conn_del()") Cc: stable@vger.kernel.org Signed-off-by: Runyu Xiao Signed-off-by: Luiz Augusto von Dentz --- diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 62133eef9d2f..036d887dec34 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -1775,19 +1775,13 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err) disable_delayed_work_sync(&conn->info_timer); disable_delayed_work_sync(&conn->id_addr_timer); + cancel_work_sync(&conn->pending_rx_work); + mutex_lock(&conn->lock); kfree_skb(conn->rx_skb); skb_queue_purge(&conn->pending_rx); - - /* 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); - ida_destroy(&conn->tx_ida); l2cap_unregister_all_users(conn);