uvcvideo: Don't accept to change the format when buffers are allocated.

From: Laurent Pinchart <laurent.pinchart@skynet.be>

Setting a new frame format or size will likely change the buffer size required
to store a complete video frame. To avoid a buffer overflow, don't allow
VIDIOC_S_FMT calls when video buffers are already allocated.

Priority: normal

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>

1 files changed, 14 insertions, 0 deletions

diff --git a/linux/drivers/media/video/uvc/uvc_queue.c b/linux/drivers/media/video/uvc/uvc_queue.c
index 0155752e4..f854698c4 100644
--- a/linux/drivers/media/video/uvc/uvc_queue.c
+++ b/linux/drivers/media/video/uvc/uvc_queue.c
@@ -172,6 +172,20 @@ int uvc_free_buffers(struct uvc_video_queue *queue)
 	return 0;
 }
 
+/*
+ * Check if buffers have been allocated.
+ */
+int uvc_queue_allocated(struct uvc_video_queue *queue)
+{
+	int allocated;
+
+	mutex_lock(&queue->mutex);
+	allocated = queue->count != 0;
+	mutex_unlock(&queue->mutex);
+
+	return allocated;
+}
+
 static void __uvc_query_buffer(struct uvc_buffer *buf,
 		struct v4l2_buffer *v4l2_buf)
 {