2022-01-06 13:00:58

by Michael S. Tsirkin

Subject: [PATCH] virtio_ring: mark ring unused on error

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" <[email protected]>
Cc: Jiasheng Jiang <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
---
drivers/virtio/virtio_ring.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 028b05d44546..962f1477b1fa 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1197,8 +1197,10 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
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 */
}
--
MST

2022-01-07 02:25:06

by Jason Wang

Subject: Re: [PATCH] virtio_ring: mark ring unused on error

On Thu, Jan 6, 2022 at 9:00 PM Michael S. Tsirkin <[email protected]> wrote:
>
> 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" <[email protected]>
> Cc: Jiasheng Jiang <[email protected]>
> Signed-off-by: Michael S. Tsirkin <[email protected]>

Acked-by: Jason Wang <[email protected]>

> ---
> drivers/virtio/virtio_ring.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 028b05d44546..962f1477b1fa 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -1197,8 +1197,10 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
> 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 */
> }
> --
> MST
>