diff options
author | Alexander Popov <alex.popov@linux.com> | 2019-11-03 23:17:19 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-28 18:26:18 +0100 |
commit | 7f8286d2b526a86d9bbdf20690b4245d0ea1fac3 (patch) | |
tree | 3089cbadc3c7c98a972ad0059570a9f21fe69806 /drivers/media | |
parent | 840e3e22c41ce8629fa2e2fb83dd7d4273b5caec (diff) |
media: vivid: Fix wrong locking that causes race conditions on streaming stop
commit 6dcd5d7a7a29c1e4b8016a06aed78cd650cd8c27 upstream.
There is the same incorrect approach to locking implemented in
vivid_stop_generating_vid_cap(), vivid_stop_generating_vid_out() and
sdr_cap_stop_streaming().
These functions are called during streaming stopping with vivid_dev.mutex
locked. And they all do the same mistake while stopping their kthreads,
which need to lock this mutex as well. See the example from
vivid_stop_generating_vid_cap():
/* shutdown control thread */
vivid_grab_controls(dev, false);
mutex_unlock(&dev->mutex);
kthread_stop(dev->kthread_vid_cap);
dev->kthread_vid_cap = NULL;
mutex_lock(&dev->mutex);
But when this mutex is unlocked, another vb2_fop_read() can lock it
instead of vivid_thread_vid_cap() and manipulate the buffer queue.
That causes a use-after-free access later.
To fix those issues let's:
1. avoid unlocking the mutex in vivid_stop_generating_vid_cap(),
vivid_stop_generating_vid_out() and sdr_cap_stop_streaming();
2. use mutex_trylock() with schedule_timeout_uninterruptible() in
the loops of the vivid kthread handlers.
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: <stable@vger.kernel.org> # for v3.18 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/media')
-rw-r--r-- | drivers/media/platform/vivid/vivid-kthread-cap.c | 8 | ||||
-rw-r--r-- | drivers/media/platform/vivid/vivid-kthread-out.c | 8 | ||||
-rw-r--r-- | drivers/media/platform/vivid/vivid-sdr-cap.c | 8 |
3 files changed, 15 insertions, 9 deletions
diff --git a/drivers/media/platform/vivid/vivid-kthread-cap.c b/drivers/media/platform/vivid/vivid-kthread-cap.c index 81ba454a6d95..1e34ee16b792 100644 --- a/drivers/media/platform/vivid/vivid-kthread-cap.c +++ b/drivers/media/platform/vivid/vivid-kthread-cap.c @@ -763,7 +763,11 @@ static int vivid_thread_vid_cap(void *data) if (kthread_should_stop()) break; - mutex_lock(&dev->mutex); + if (!mutex_trylock(&dev->mutex)) { + schedule_timeout_uninterruptible(1); + continue; + } + cur_jiffies = jiffies; if (dev->cap_seq_resync) { dev->jiffies_vid_cap = cur_jiffies; @@ -916,8 +920,6 @@ void vivid_stop_generating_vid_cap(struct vivid_dev *dev, bool *pstreaming) /* shutdown control thread */ vivid_grab_controls(dev, false); - mutex_unlock(&dev->mutex); kthread_stop(dev->kthread_vid_cap); dev->kthread_vid_cap = NULL; - mutex_lock(&dev->mutex); } diff --git a/drivers/media/platform/vivid/vivid-kthread-out.c b/drivers/media/platform/vivid/vivid-kthread-out.c index 2c5dbdcb576a..ba38602680d6 100644 --- a/drivers/media/platform/vivid/vivid-kthread-out.c +++ b/drivers/media/platform/vivid/vivid-kthread-out.c @@ -147,7 +147,11 @@ static int vivid_thread_vid_out(void *data) if (kthread_should_stop()) break; - mutex_lock(&dev->mutex); + if (!mutex_trylock(&dev->mutex)) { + schedule_timeout_uninterruptible(1); + continue; + } + cur_jiffies = jiffies; if (dev->out_seq_resync) { dev->jiffies_vid_out = cur_jiffies; @@ -301,8 +305,6 @@ void vivid_stop_generating_vid_out(struct vivid_dev *dev, bool *pstreaming) /* shutdown control thread */ vivid_grab_controls(dev, false); - mutex_unlock(&dev->mutex); kthread_stop(dev->kthread_vid_out); dev->kthread_vid_out = NULL; - mutex_lock(&dev->mutex); } diff --git a/drivers/media/platform/vivid/vivid-sdr-cap.c b/drivers/media/platform/vivid/vivid-sdr-cap.c index 082c401764ce..4866f42c8027 100644 --- a/drivers/media/platform/vivid/vivid-sdr-cap.c +++ b/drivers/media/platform/vivid/vivid-sdr-cap.c @@ -151,7 +151,11 @@ static int vivid_thread_sdr_cap(void *data) if (kthread_should_stop()) break; - mutex_lock(&dev->mutex); + if (!mutex_trylock(&dev->mutex)) { + schedule_timeout_uninterruptible(1); + continue; + } + cur_jiffies = jiffies; if (dev->sdr_cap_seq_resync) { dev->jiffies_sdr_cap = cur_jiffies; @@ -311,10 +315,8 @@ static void sdr_cap_stop_streaming(struct vb2_queue *vq) } /* shutdown control thread */ - mutex_unlock(&dev->mutex); kthread_stop(dev->kthread_sdr_cap); dev->kthread_sdr_cap = NULL; - mutex_lock(&dev->mutex); } const struct vb2_ops vivid_sdr_cap_qops = { |