[media] videobuf2-core: Verify planes lengths for output buffers

For output buffers application provide to the kernel the number of bytes
they stored in each plane of the buffer. Verify that the value is
smaller than or equal to the plane length.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/v4l2-core/videobuf2-core.c

@@ -333,6 +333,41 @@ static int __verify_planes_array(struct vb2_buffer *vb, const struct v4l2_buffer
 	return 0;
 }
 
+/**
+ * __verify_length() - Verify that the bytesused value for each plane fits in
+ * the plane length and that the data offset doesn't exceed the bytesused value.
+ */
+static int __verify_length(struct vb2_buffer *vb, const struct v4l2_buffer *b)
+{
+	unsigned int length;
+	unsigned int plane;
+
+	if (!V4L2_TYPE_IS_OUTPUT(b->type))
+		return 0;
+
+	if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
+		for (plane = 0; plane < vb->num_planes; ++plane) {
+			length = (b->memory == V4L2_MEMORY_USERPTR)
+			       ? b->m.planes[plane].length
+			       : vb->v4l2_planes[plane].length;
+
+			if (b->m.planes[plane].bytesused > length)
+				return -EINVAL;
+			if (b->m.planes[plane].data_offset >=
+			    b->m.planes[plane].bytesused)
+				return -EINVAL;
+		}
+	} else {
+		length = (b->memory == V4L2_MEMORY_USERPTR)
+		       ? b->length : vb->v4l2_planes[0].length;
+
+		if (b->bytesused > length)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
  * __buffer_in_use() - return true if the buffer is in use and
  * the queue cannot be freed (by the means of REQBUFS(0)) call
@@ -1167,6 +1202,10 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	struct vb2_queue *q = vb->vb2_queue;
 	int ret;
 
+	ret = __verify_length(vb, b);
+	if (ret < 0)
+		return ret;
+
 	switch (q->memory) {
 	case V4L2_MEMORY_MMAP:
 		ret = __qbuf_mmap(vb, b);