vhost_vsock_handle_tx_kick() already holds the mutex during its call to vhost_get_vq_desc(). All we have to do here is take the same lock during virtqueue clean-up and we mitigate the reported issues. Also WARN() as a precautionary measure. The purpose of this is to capture possible future race conditions which may pop up over time. Link: https://syzkaller.appspot.com/bug?extid=279432d30d825e63ba00 Cc: <stable@xxxxxxxxxxxxxxx> Reported-by: syzbot+adc3cb32385586bec859@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx> --- drivers/vhost/vhost.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 59edb5a1ffe28..ef7e371e3e649 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -693,6 +693,15 @@ void vhost_dev_cleanup(struct vhost_dev *dev) int i; for (i = 0; i < dev->nvqs; ++i) { + /* No workers should run here by design. However, races have + * previously occurred where drivers have been unable to flush + * all work properly prior to clean-up. Without a successful + * flush the guest will malfunction, but avoiding host memory + * corruption in those cases does seem preferable. + */ + WARN_ON(mutex_is_locked(&dev->vqs[i]->mutex)); + + 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 +709,7 @@ 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) -- 2.35.1.616.g0bdcbb4464-goog
