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vhost: Don't call access_ok() when using IOTLB

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commit 0210a8db2aeca393fb3067e234967877e3146266 upstream.

When the IOTLB device is enabled, the vring addresses we get
from userspace are GIOVAs. It is thus wrong to pass them down
to access_ok() which only takes HVAs.

Access validation is done at prefetch time with IOTLB. Teach
vq_access_ok() about that by moving the (vq->iotlb) check
from vhost_vq_access_ok() to vq_access_ok(). This prevents
vhost_vring_set_addr() to fail when verifying the accesses.
No behavior change for vhost_vq_access_ok().

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1883084
Fixes: 6b1e6cc785 ("vhost: new device IOTLB API")
Cc: jasowang@redhat.com
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Greg Kurz <groug@kaod.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/160171931213.284610.2052489816407219136.stgit@bahia.lan
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kurz 2020-10-03 12:01:52 +02:00 • committed by Greg Kroah-Hartman
commit 57b47abc1a
1 changed files with 5 additions and 4 deletions
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9
drivers/vhost/vhost.c
View file

@ -1299,6 +1299,11 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
struct vring_used __user *used)
{
/* If an IOTLB device is present, the vring addresses are
* GIOVAs. Access validation occurs at prefetch time. */
if (vq->iotlb)
return true;
return access_ok(desc, vhost_get_desc_size(vq, num)) &&
access_ok(avail, vhost_get_avail_size(vq, num)) &&
access_ok(used, vhost_get_used_size(vq, num));
@ -1394,10 +1399,6 @@ bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
if (!vq_log_access_ok(vq, vq->log_base))
return false;
/* Access validation occurs at prefetch time with IOTLB */
if (vq->iotlb)
return true;
return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
}
EXPORT_SYMBOL_GPL(vhost_vq_access_ok);