On Wed, Mar 02, 2022 at 10:34:46AM +0100, Stefano Garzarella wrote: > 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 Right. I want to queue this but I would like to get a warning so we can detect issues like [2] before they cause more issues. > > > > 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 > >
