media: imon: fix a race condition in send_packet()
authorGautam Menghani <gautammenghani201@gmail.com>
Wed, 19 Oct 2022 05:02:14 +0000 (06:02 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 31 Dec 2022 12:32:16 +0000 (13:32 +0100)
commit3f8b24ab0d0001ef9cb13400add90a38aaa63173
tree16e6b0c0103d4bf389508d2448858e3dc563a324
parentf38df8984ef1b45ba23888d0e232cc21a95bd04b
media: imon: fix a race condition in send_packet()

[ Upstream commit 813ceef062b53d68f296aa3cb944b21a091fabdb ]

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: 21677cfc562a ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/media/rc/imon.c