On Wed, Mar 02, 2022 at 07:54:21AM +0000, Lee Jones wrote:
vhost_vsock_handle_tx_kick() already holds the mutex during its call
to vhost_get_vq_desc(). All we have to do is take the same lock
during virtqueue clean-up and we mitigate the reported issues.
Link: https://syzkaller.appspot.com/bug?extid=279432d30d825e63ba00
This issue is similar to [1] that should be already fixed upstream by
[2].
However I think this patch would have prevented some issues, because
vhost_vq_reset() sets vq->private to NULL, preventing the worker from
running.
Anyway I think that when we enter in vhost_dev_cleanup() the worker
should be already stopped, so it shouldn't be necessary to take the
mutex. But in order to prevent future issues maybe it's better to take
them, so:
Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
[1]
https://syzkaller.appspot.com/bug?id=993d8b5e64393ed9e6a70f9ae4de0119c605a822
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58da53ffd70294ebea8ecd0eb45fd0d74add9f9
Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: syzbot+adc3cb32385586bec859@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
drivers/vhost/vhost.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 59edb5a1ffe28..bbaff6a5e21b8 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -693,6 +693,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
int i;
for (i = 0; i < dev->nvqs; ++i) {
+ mutex_lock(&dev->vqs[i]->mutex);
if (dev->vqs[i]->error_ctx)
eventfd_ctx_put(dev->vqs[i]->error_ctx);
if (dev->vqs[i]->kick)
@@ -700,6 +701,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
if (dev->vqs[i]->call_ctx.ctx)
eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
vhost_vq_reset(dev, dev->vqs[i]);
+ mutex_unlock(&dev->vqs[i]->mutex);
}
vhost_dev_free_iovecs(dev);
if (dev->log_ctx)
--
2.35.1.574.g5d30c73bfb-goog
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