diff options
| author | Alexey Khoroshilov <khoroshilov@ispras.ru> | 2013-11-09 18:28:43 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <m.chehab@samsung.com> | 2013-11-29 12:18:25 -0200 |
| commit | 6633327d59067fe16128d66968cd50a10ca7a09c (patch) | |
| tree | 8b15c43911b272535286e227d5263010a52e2438 /drivers/media | |
| parent | 858559a29258a30d9f4839286b4aca6ab8c5c8d6 (diff) | |
[media] dvb_demux: fix deadlock in dmx_section_feed_release_filter()
dmx_section_feed_release_filter() locks dvbdmx->mutex and
if the feed is still filtering, it calls feed->stop_filtering(feed).
stop_filtering() is implemented by dmx_section_feed_stop_filtering()
that first of all try to lock the same mutex: dvbdmx->mutex.
That leads to a deadlock.
It does not happen often in practice because all callers of
release_filter() stop filtering by themselves.
So the problem can happen in case of race condition only.
The patch releases dvbdmx->mutex before call to feed->stop_filtering(feed)
and reacquires the mutex after that.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Diffstat (limited to 'drivers/media')
| -rw-r--r-- | drivers/media/dvb-core/dvb_demux.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/media/dvb-core/dvb_demux.c b/drivers/media/dvb-core/dvb_demux.c index 58de4410c525..25f3c6484610 100644 --- a/drivers/media/dvb-core/dvb_demux.c +++ b/drivers/media/dvb-core/dvb_demux.c @@ -1032,8 +1032,13 @@ static int dmx_section_feed_release_filter(struct dmx_section_feed *feed, return -EINVAL; } - if (feed->is_filtering) + if (feed->is_filtering) { + /* release dvbdmx->mutex as far as + it is acquired by stop_filtering() itself */ + mutex_unlock(&dvbdmx->mutex); feed->stop_filtering(feed); + mutex_lock(&dvbdmx->mutex); + } spin_lock_irq(&dvbdmx->lock); f = dvbdmxfeed->filter; |