[PATCH 5.10 532/563] virtio_ring: mark ring unused on error

[Greg Kroah-Hartman]

From: Michael S. Tsirkin <mst@xxxxxxxxxx>

commit 1861ba626ae9b98136f3e504208cdef6b29cd3ec upstream.

A recently added error path does not mark ring unused when exiting on
OOM, which will lead to BUG on the next entry in debug builds.

TODO: refactor code so we have START_USE and END_USE in the same function.

Fixes: fc6d70f40b3d ("virtio_ring: check desc == NULL when using indirect with packed")
Cc: "Xuan Zhuo" <xuanzhuo@xxxxxxxxxxxxxxxxx>
Cc: Jiasheng Jiang <jiasheng@xxxxxxxxxxx>
Reviewed-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1124,8 +1124,10 @@ static inline int virtqueue_add_packed(s
 	if (virtqueue_use_indirect(_vq, total_sg)) {
 		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
 						    in_sgs, data, gfp);
-		if (err != -ENOMEM)
+		if (err != -ENOMEM) {
+			END_USE(vq);
 			return err;
+		}
 
 		/* fall back on direct */
 	}