5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luiz Augusto von Dentz [ Upstream commit f1a8f402f13f94263cf349216c257b2985100927 ] This fixes the following deadlock introduced by 39a92a55be13 ("bluetooth/l2cap: sync sock recv cb and release") ============================================ WARNING: possible recursive locking detected 6.10.0-rc3-g4029dba6b6f1 #6823 Not tainted -------------------------------------------- kworker/u5:0/35 is trying to acquire lock: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_sock_recv_cb+0x44/0x1e0 but task is already holding lock: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_get_chan_by_scid+0xaf/0xd0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&chan->lock#2/1); lock(&chan->lock#2/1); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u5:0/35: #0: ffff888002b8a940 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work+0x750/0x930 #1: ffff888002c67dd0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x44e/0x930 #2: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_get_chan_by_scid+0xaf/0xd0 To fix the original problem this introduces l2cap_chan_lock at l2cap_conless_channel to ensure that l2cap_sock_recv_cb is called with chan->lock held. Fixes: 89e856e124f9 ("bluetooth/l2cap: sync sock recv cb and release") Signed-off-by: Luiz Augusto von Dentz [ Karl Mehltretter: backport only the l2cap_core.c changes. The HCI changes are from an unrelated patch accidentally squashed into this commit. The l2cap_sock.c change removes locking added by 89e856e124f9, which is absent from 5.15.y, so the quoted deadlock cannot occur. The core changes are needed because c531e63871c0 was backported without the matching lock. ] Assisted-by: LLM Signed-off-by: Karl Mehltretter Signed-off-by: Sasha Levin --- net/bluetooth/l2cap_core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index ece7d37339c46..bb514810945ab 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -8003,6 +8003,8 @@ static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm, BT_DBG("chan %p, len %d", chan, skb->len); + l2cap_chan_lock(chan); + if (chan->state != BT_BOUND && chan->state != BT_CONNECTED) goto drop; @@ -8020,6 +8022,7 @@ static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm, } drop: + l2cap_chan_unlock(chan); l2cap_chan_put(chan); free_skb: kfree_skb(skb); -- 2.53.0