Date:   Thu, 6 Jan 2022 08:00:48 -0500
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
        Jiasheng Jiang <jiasheng@iscas.ac.cn>,
        Jason Wang <jasowang@redhat.com>,
        virtualization@lists.linux-foundation.org
Subject: [PATCH] virtio_ring: mark ring unused on error
Message-ID: <20220106130046.422417-1-mst@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
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Precedence: bulk

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@linux.alibaba.com>
Cc: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 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