[PATCH 6.18 122/309] Bluetooth: L2CAP: Fix deadlock in l2cap_conn_del()

Greg Kroah-Hartman
2026-03-31T17:01:58Z

From: Hyunwoo Kim <imv4bel@gmail.com>

[ Upstream commit 00fdebbbc557a2fc21321ff2eaa22fd70c078608 ]

l2cap_conn_del() calls cancel_delayed_work_sync() for both info_timer
and id_addr_timer while holding conn->lock. However, the work functions
l2cap_info_timeout() and l2cap_conn_update_id_addr() both acquire
conn->lock, creating a potential AB-BA deadlock if the work is already
executing when l2cap_conn_del() takes the lock.

Move the work cancellations before acquiring conn->lock and use
disable_delayed_work_sync() to additionally prevent the works from
being rearmed after cancellation, consistent with the pattern used in
hci_conn_del().

Fixes: ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/bluetooth/l2cap_core.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 5bd5561a8dbf5..734cbb5dc1bfa 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -1748,6 +1748,9 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)

BT_DBG("hcon %p conn %p, err %d", hcon, conn, err);

+ disable_delayed_work_sync(&conn->info_timer);
+ disable_delayed_work_sync(&conn->id_addr_timer);
+
mutex_lock(&conn->lock);

kfree_skb(conn->rx_skb);
@@ -1763,8 +1766,6 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)

ida_destroy(&conn->tx_ida);

- cancel_delayed_work_sync(&conn->id_addr_timer);
-
l2cap_unregister_all_users(conn);

/* Force the connection to be immediately dropped */
@@ -1783,9 +1784,6 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
l2cap_chan_put(chan);
}

- if (conn->info_state & L2CAP_INFO_FEAT_MASK_REQ_SENT)
- cancel_delayed_work_sync(&conn->info_timer);
-
hci_chan_del(conn->hchan);
conn->hchan = NULL;

--
2.51.0