[PATCH] vb2: check if vb2_fop_write/read is allowed

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Return -EINVAL if read() or write() is not supported by the queue. This
makes it possible to provide both vb2_fop_read and vb2_fop_write in a
struct v4l2_file_operations since the vb2_fop_* function will check if
the file operation is allowed.

A similar check exists in __vb2_init_fileio() which is called from
__vb2_perform_fileio(), but that check is only done if no file I/O is
active. So the sequence of read() followed by write() would be allowed,
which is obviously a bug.

In addition, vb2_fop_write/read should always return -EINVAL if the
operation is not allowed, and by putting the check in the lower levels
of the code it is possible that other error codes are returned (EBUSY
or ERESTARTSYS).

All these issues are avoided by just doing a quick explicit check.

Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index bc08a82..167c1d9 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -3416,6 +3416,8 @@ ssize_t vb2_fop_write(struct file *file, const char __user *buf,
 	struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
 	int err = -EBUSY;
 
+	if (!(vdev->queue->io_modes & VB2_WRITE))
+		return -EINVAL;
 	if (lock && mutex_lock_interruptible(lock))
 		return -ERESTARTSYS;
 	if (vb2_queue_is_busy(vdev, file))
@@ -3438,6 +3440,8 @@ ssize_t vb2_fop_read(struct file *file, char __user *buf,
 	struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
 	int err = -EBUSY;
 
+	if (!(vdev->queue->io_modes & VB2_READ))
+		return -EINVAL;
 	if (lock && mutex_lock_interruptible(lock))
 		return -ERESTARTSYS;
 	if (vb2_queue_is_busy(vdev, file))
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Input]     [Video for Linux]     [Gstreamer Embedded]     [Mplayer Users]     [Linux USB Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [Yosemite Backpacking]
  Powered by Linux