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vhost: validate log when IOTLB is enabled 

Vq log_base is the userspace address of bitmap which has nothing to do
with IOTLB. So it needs to be validated unconditionally otherwise we
may try use 0 as log_base which may lead to pin pages that will lead
unexpected result (e.g trigger BUG_ON() in set_bit_to_user()).

Fixes: 6b1e6cc785 ("vhost: new device IOTLB API")
Reported-by: syzbot+6304bf97ef436580fede@syzkaller.appspotmail.com
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2018-03-29 16:00:04 +08:00 committed by David S. Miller
parent 58f101bf87
commit d65026c6c6
1 changed files with 6 additions and 8 deletions
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14
drivers/vhost/vhost.c
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@ -1244,14 +1244,12 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq,
/* Caller should have vq mutex and device mutex */
int vhost_vq_access_ok(struct vhost_virtqueue *vq)
{
if (vq->iotlb) {
/* When device IOTLB was used, the access validation
* will be validated during prefetching.
*/
return 1;
}
return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
vq_log_access_ok(vq, vq->log_base);
int ret = vq_log_access_ok(vq, vq->log_base);
if (ret || vq->iotlb)
return ret;
return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
}
EXPORT_SYMBOL_GPL(vhost_vq_access_ok);