This is a note to let you know that I've just added the patch titled Bluetooth: hci_serdev: call init_rwsem() before p->open() to the 5.17-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-hci_serdev-call-init_rwsem-before-p-open.patch and it can be found in the queue-5.17 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 6bd0ce08f955176725dd03765ffc71cd400ef828 Author: Pavel Skripkin <paskripkin@xxxxxxxxx> Date: Thu Jan 13 16:27:04 2022 +0300 Bluetooth: hci_serdev: call init_rwsem() before p->open() [ Upstream commit 9d7cbe2b9cf5f650067df4f402fdd799d4bbb4e1 ] kvartet reported, that hci_uart_tx_wakeup() uses uninitialized rwsem. The problem was in wrong place for percpu_init_rwsem() call. hci_uart_proto::open() may register a timer whose callback may call hci_uart_tx_wakeup(). There is a chance, that hci_uart_register_device() thread won't be fast enough to call percpu_init_rwsem(). Fix it my moving percpu_init_rwsem() call before p->open(). INFO: trying to register non-static key. The code is fine but needs lockdep annotation, or maybe you didn't initialize this object before use? turning off the locking correctness validator. CPU: 2 PID: 18524 Comm: syz-executor.5 Not tainted 5.16.0-rc6 #9 ... Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 assign_lock_key kernel/locking/lockdep.c:951 [inline] register_lock_class+0x148d/0x1950 kernel/locking/lockdep.c:1263 __lock_acquire+0x106/0x57e0 kernel/locking/lockdep.c:4906 lock_acquire kernel/locking/lockdep.c:5637 [inline] lock_acquire+0x1ab/0x520 kernel/locking/lockdep.c:5602 percpu_down_read_trylock include/linux/percpu-rwsem.h:92 [inline] hci_uart_tx_wakeup+0x12e/0x490 drivers/bluetooth/hci_ldisc.c:124 h5_timed_event+0x32f/0x6a0 drivers/bluetooth/hci_h5.c:188 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 Fixes: d73e17281665 ("Bluetooth: hci_serdev: Init hci_uart proto_lock to avoid oops") Reported-by: Yiru Xu <xyru1999@xxxxxxxxx> Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx> Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/bluetooth/hci_serdev.c b/drivers/bluetooth/hci_serdev.c index 3b00d82d36cf..4cda890ce647 100644 --- a/drivers/bluetooth/hci_serdev.c +++ b/drivers/bluetooth/hci_serdev.c @@ -305,6 +305,8 @@ int hci_uart_register_device(struct hci_uart *hu, if (err) return err; + percpu_init_rwsem(&hu->proto_lock); + err = p->open(hu); if (err) goto err_open; @@ -327,7 +329,6 @@ int hci_uart_register_device(struct hci_uart *hu, INIT_WORK(&hu->init_ready, hci_uart_init_work); INIT_WORK(&hu->write_work, hci_uart_write_work); - percpu_init_rwsem(&hu->proto_lock); /* Only when vendor specific setup callback is provided, consider * the manufacturer information valid. This avoids filling in the