The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in
implementation of the mmap() and get_unmapped_area() file operations
that calls vb2_mmap() and vb2_get_unmapped_area() on the queue
associated with the video device. Neither the
vb2_fop_mmap/vb2_fop_get_unmapped_area nor the
v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any
lock, leading to race conditions between mmap/get_unmapped_area and
other buffer-related ioctls such as VIDIOC_REQBUFS.
Fix it by taking the queue or device lock around the vb2_mmap() and
vb2_get_unmapped_area() calls.
Signed-off-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
---
drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c
b/drivers/media/v4l2-core/videobuf2-core.c
index 9fc4bab..c9b50c7 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf);
int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma)
{
struct video_device *vdev = video_devdata(file);
+ struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
+ int err;
- return vb2_mmap(vdev->queue, vma);
+ if (lock && mutex_lock_interruptible(lock))
+ return -ERESTARTSYS;
+ err = vb2_mmap(vdev->queue, vma);
+ if (lock)
+ mutex_unlock(lock);
+ return err;
}
EXPORT_SYMBOL_GPL(vb2_fop_mmap);
@@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct file
*file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct video_device *vdev = video_devdata(file);
+ struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
+ int ret;
- return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags);
+ if (lock && mutex_lock_interruptible(lock))
+ return -ERESTARTSYS;
+ ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags);
+ if (lock)
+ mutex_unlock(lock);
+ return ret;
}
EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area);
#endif
--
Regards,
Laurent Pinchart
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