[Devel] [PATCH RH7] vhost: do not try to access device IOTLB when not initialized

[Pavel Tikhomirov]

We have GPF when Kasan checks umem->umem_tree before dereferencing it
later in vhost_umem_interval_tree_iter_first, and it is zero.

https://jira.sw.ru/browse/PSBM-90313

MS commit 6f3180afbb22 ("vhost: do not try to access device IOTLB when
not initialized")

The code will try to access dev->iotlb when processing
VHOST_IOTLB_INVALIDATE even if it was not initialized which may lead
to NULL pointer dereference. Fixes this by check dev->iotlb before.

Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
Signed-off-by: Jason Wang <jasowang at redhat.com>
Acked-by: Michael S. Tsirkin <mst at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 drivers/vhost/vhost.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 412585876c38..9828070ef279 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -997,6 +997,10 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
 		vhost_iotlb_notify_vq(dev, msg);
 		break;
 	case VHOST_IOTLB_INVALIDATE:
+		if (!dev->iotlb) {
+			ret = -EFAULT;
+			break;
+		}
 		vhost_vq_meta_reset(dev);
 		vhost_del_umem_range(dev->iotlb, msg->iova,
 				     msg->iova + msg->size - 1);
-- 
2.17.1