diff options
| author | Matthew Leach <matthew@mattleach.net> | 2016-07-08 09:04:27 -0300 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2016-08-17 12:58:31 -0400 |
| commit | bdf3214616dd38384c9716ce96a18b779e233224 (patch) | |
| tree | b9712dc7cae5f034499f4783d22d2d22ffb738d9 | |
| parent | 47c1628a3d5ea9803b4175ad8eb0b0f577f16e49 (diff) | |
[media] media: usbtv: prevent access to free'd resources
[ Upstream commit 2a00932f082aff93c3a55426e0c7af6d0ec03997 ]
When disconnecting the usbtv device, the sound card is unregistered
from ALSA and the snd member of the usbtv struct is set to NULL. If
the usbtv snd_trigger work is running, this can cause a race condition
where the kernel will attempt to access free'd resources, shown in
[1].
This patch fixes the disconnection code by cancelling any snd_trigger
work before unregistering the sound card from ALSA and checking that
the snd member still exists in the work function.
[1]:
usb 3-1.2: USB disconnect, device number 6
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: [<ffffffff81093850>] process_one_work+0x30/0x480
PGD 405bbf067 PUD 405bbe067 PMD 0
Call Trace:
[<ffffffff81093ce8>] worker_thread+0x48/0x4e0
[<ffffffff81093ca0>] ? process_one_work+0x480/0x480
[<ffffffff81093ca0>] ? process_one_work+0x480/0x480
[<ffffffff81099998>] kthread+0xd8/0xf0
[<ffffffff815c73c2>] ret_from_fork+0x22/0x40
[<ffffffff810998c0>] ? kthread_worker_fn+0x170/0x170
---[ end trace 0f3dac5c1a38e610 ]---
Signed-off-by: Matthew Leach <matthew@mattleach.net>
Tested-by: Peter Sutton <foxxy@foxdogstudios.com>
Cc: stable@vger.kernel.org
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
| -rw-r--r-- | drivers/media/usb/usbtv/usbtv-audio.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/media/usb/usbtv/usbtv-audio.c b/drivers/media/usb/usbtv/usbtv-audio.c index 78c12d22dfbb..5dab02432e82 100644 --- a/drivers/media/usb/usbtv/usbtv-audio.c +++ b/drivers/media/usb/usbtv/usbtv-audio.c @@ -278,6 +278,9 @@ static void snd_usbtv_trigger(struct work_struct *work) { struct usbtv *chip = container_of(work, struct usbtv, snd_trigger); + if (!chip->snd) + return; + if (atomic_read(&chip->snd_stream)) usbtv_audio_start(chip); else @@ -378,6 +381,8 @@ err: void usbtv_audio_free(struct usbtv *usbtv) { + cancel_work_sync(&usbtv->snd_trigger); + if (usbtv->snd && usbtv->udev) { snd_card_free(usbtv->snd); usbtv->snd = NULL; |