Commit 0210a8db authored Oct 03, 2020 by Greg Kurz Committed by Michael S. Tsirkin Oct 04, 2020

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

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: 6b1e6cc7 ("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>

parent 37787e9f

drivers/vhost/vhost.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -1290,6 +1290,11 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
		vring_used_t __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));
		@@ -1383,10 +1388,6 @@ 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);

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