linux-kernel - [PATCH v3 2/3] vhost: Use vhost_get_used_size() in vhost_vring_set

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Date:   Sat, 03 Oct 2020 12:02:03 +0200
From:   Greg Kurz <groug@...d.org>
To:     "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>
Cc:     kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        qemu-devel@...gnu.org, Laurent Vivier <laurent@...ier.eu>,
        David Gibson <david@...son.dropbear.id.au>
Subject: [PATCH v3 2/3] vhost: Use vhost_get_used_size() in
 vhost_vring_set_addr()

The open-coded computation of the used size doesn't take the event
into account when the VIRTIO_RING_F_EVENT_IDX feature is present.
Fix that by using vhost_get_used_size().

Signed-off-by: Greg Kurz <groug@...d.org>
---
 drivers/vhost/vhost.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index c3b49975dc28..9d2c225fb518 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1519,8 +1519,7 @@ static long vhost_vring_set_addr(struct vhost_dev *d,
 		/* Also validate log access for used ring if enabled. */
 		if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
 			!log_access_ok(vq->log_base, a.log_guest_addr,
-				sizeof *vq->used +
-				vq->num * sizeof *vq->used->ring))
+				       vhost_get_used_size(vq, vq->num)))
 			return -EINVAL;
 	}