The function send_packet() has a race condition as follows:
func send_packet()
{
// do work
call usb_submit_urb()
mutex_unlock()
wait_for_event_interruptible() <-- lock gone
mutex_lock()
}
func vfd_write()
{
mutex_lock()
call send_packet() <- prev call is not completed
mutex_unlock()
}
When the mutex is unlocked and the function send_packet() waits for the
call to complete, vfd_write() can start another call, which leads to the
"URB submitted while active" warning in usb_submit_urb().
Fix this by removing the mutex_unlock() call in send_packet() and using
mutex_lock_interruptible().
Link: https://syzkaller.appspot.com/bug?id=e378e6a51fbe6c5cc43e34f131cc9a315ef0337e
Fixes: 21677cfc56 ("V4L/DVB: ir-core: add imon driver")
Reported-by: syzbot+0c3cb6dc05fbbdc3ad66@syzkaller.appspotmail.com
Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
813ceef062