[net] vhost: reset metadata cache when initializing new IOTLB

Message ID 1533699784-4950-1-git-send-email-jasowang@redhat.com
State Accepted
Delegated to: David Miller
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Series
  • [net] vhost: reset metadata cache when initializing new IOTLB
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Commit Message

Jason Wang Aug. 8, 2018, 3:43 a.m.
We need to reset metadata cache during new IOTLB initialization,
otherwise the stale pointers to previous IOTLB may be still accessed
which will lead a use after free.

Reported-by: syzbot+c51e6736a1bf614b3272@syzkaller.appspotmail.com
Fixes: f88949138058 ("vhost: introduce O(1) vq metadata cache")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/vhost.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

David Miller Aug. 8, 2018, 4:45 p.m. | #1
From: Jason Wang <jasowang@redhat.com>
Date: Wed,  8 Aug 2018 11:43:04 +0800

> We need to reset metadata cache during new IOTLB initialization,
> otherwise the stale pointers to previous IOTLB may be still accessed
> which will lead a use after free.
> 
> Reported-by: syzbot+c51e6736a1bf614b3272@syzkaller.appspotmail.com
> Fixes: f88949138058 ("vhost: introduce O(1) vq metadata cache")
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Applied and queued up for -stable, thanks Jason.

Patch

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a502f1a..ed31145 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1560,9 +1560,12 @@  int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
 	d->iotlb = niotlb;
 
 	for (i = 0; i < d->nvqs; ++i) {
-		mutex_lock(&d->vqs[i]->mutex);
-		d->vqs[i]->iotlb = niotlb;
-		mutex_unlock(&d->vqs[i]->mutex);
+		struct vhost_virtqueue *vq = d->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vq->iotlb = niotlb;
+		__vhost_vq_meta_reset(vq);
+		mutex_unlock(&vq->mutex);
 	}
 
 	vhost_umem_clean(oiotlb);