From 6f3180afbb22106d96a1320e175562f36a4d3506 Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@redhat.com>
Date: Tue, 23 Jan 2018 17:27:26 +0800
Subject: [PATCH] vhost: do not try to access device IOTLB when not initialized
Git-commit: 6f3180afbb22106d96a1320e175562f36a4d3506
Patch-mainline: v4.15
References: bsc#1051510

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@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/vhost/vhost.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 549771a0cd8b..5727b186b3ca 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1015,6 +1015,10 @@ 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);
-- 
2.18.0