media: vivid: Fix wrong locking that causes race conditions on streaming stop
commit 6dcd5d7a7a
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>
5.4-rM2-2.2.x-imx-squashed
parent
92edb64da9
commit
5aa7ad7e99
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@ -796,7 +796,11 @@ static int vivid_thread_vid_cap(void *data)
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if (kthread_should_stop())
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break;
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mutex_lock(&dev->mutex);
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if (!mutex_trylock(&dev->mutex)) {
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schedule_timeout_uninterruptible(1);
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continue;
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}
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cur_jiffies = jiffies;
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if (dev->cap_seq_resync) {
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dev->jiffies_vid_cap = cur_jiffies;
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@ -956,8 +960,6 @@ void vivid_stop_generating_vid_cap(struct vivid_dev *dev, bool *pstreaming)
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/* shutdown control thread */
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vivid_grab_controls(dev, false);
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mutex_unlock(&dev->mutex);
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kthread_stop(dev->kthread_vid_cap);
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dev->kthread_vid_cap = NULL;
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mutex_lock(&dev->mutex);
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}
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@ -143,7 +143,11 @@ static int vivid_thread_vid_out(void *data)
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if (kthread_should_stop())
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break;
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mutex_lock(&dev->mutex);
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if (!mutex_trylock(&dev->mutex)) {
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schedule_timeout_uninterruptible(1);
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continue;
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}
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cur_jiffies = jiffies;
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if (dev->out_seq_resync) {
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dev->jiffies_vid_out = cur_jiffies;
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@ -301,8 +305,6 @@ void vivid_stop_generating_vid_out(struct vivid_dev *dev, bool *pstreaming)
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/* shutdown control thread */
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vivid_grab_controls(dev, false);
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mutex_unlock(&dev->mutex);
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kthread_stop(dev->kthread_vid_out);
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dev->kthread_vid_out = NULL;
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mutex_lock(&dev->mutex);
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}
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@ -141,7 +141,11 @@ static int vivid_thread_sdr_cap(void *data)
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if (kthread_should_stop())
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break;
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mutex_lock(&dev->mutex);
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if (!mutex_trylock(&dev->mutex)) {
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schedule_timeout_uninterruptible(1);
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continue;
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}
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cur_jiffies = jiffies;
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if (dev->sdr_cap_seq_resync) {
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dev->jiffies_sdr_cap = cur_jiffies;
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@ -303,10 +307,8 @@ static void sdr_cap_stop_streaming(struct vb2_queue *vq)
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}
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/* shutdown control thread */
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mutex_unlock(&dev->mutex);
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kthread_stop(dev->kthread_sdr_cap);
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dev->kthread_sdr_cap = NULL;
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mutex_lock(&dev->mutex);
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}
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static void sdr_cap_buf_request_complete(struct vb2_buffer *vb)
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