This is a note to let you know that I've just added the patch titled Bluetooth: Fix a refcnt underflow problem for hci_conn to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bluetooth-fix-a-refcnt-underflow-problem-for-hci_conn.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From c7f59461f5a78994613afc112cdd73688aef9076 Mon Sep 17 00:00:00 2001 From: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx> Date: Wed, 4 Oct 2023 20:42:24 +0800 Subject: Bluetooth: Fix a refcnt underflow problem for hci_conn From: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx> commit c7f59461f5a78994613afc112cdd73688aef9076 upstream. Syzbot reports a warning as follows: WARNING: CPU: 1 PID: 26946 at net/bluetooth/hci_conn.c:619 hci_conn_timeout+0x122/0x210 net/bluetooth/hci_conn.c:619 ... Call Trace: <TASK> process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 </TASK> It is because the HCI_EV_SIMPLE_PAIR_COMPLETE event handler drops hci_conn directly without check Simple Pairing whether be enabled. But the Simple Pairing process can only be used if both sides have the support enabled in the host stack. Add hci_conn_ssp_enabled() for hci_conn in HCI_EV_IO_CAPA_REQUEST and HCI_EV_SIMPLE_PAIR_COMPLETE event handlers to fix the problem. Fixes: 0493684ed239 ("[Bluetooth] Disable disconnect timer during Simple Pairing") Signed-off-by: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/bluetooth/hci_event.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -4725,7 +4725,7 @@ static void hci_io_capa_request_evt(stru hci_dev_lock(hdev); conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &ev->bdaddr); - if (!conn) + if (!conn || !hci_conn_ssp_enabled(conn)) goto unlock; hci_conn_hold(conn); @@ -4970,7 +4970,7 @@ static void hci_simple_pair_complete_evt hci_dev_lock(hdev); conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &ev->bdaddr); - if (!conn) + if (!conn || !hci_conn_ssp_enabled(conn)) goto unlock; /* Reset the authentication requirement to unknown */ Patches currently in stable-queue which might be from william.xuanziyang@xxxxxxxxxx are queue-5.15/bluetooth-fix-a-refcnt-underflow-problem-for-hci_conn.patch