From 4d1ccc17f40f73313e13c84914f70ec3d40ac738 Mon Sep 17 00:00:00 2001 From: Eugenio Pérez Date: Fri, 29 Jan 2021 10:07:28 +0100 Subject: vhost: Check for valid vdev in vhost_backend_handle_iotlb_msg Not checking this can lead to invalid dev->vdev member access in vhost_device_iotlb_miss if backend issue an iotlb message in a bad timing, either maliciously or by a bug. Reproduced rebooting a guest with testpmd in txonly forward mode. #0 0x0000559ffff94394 in vhost_device_iotlb_miss ( dev=dev@entry=0x55a0012f6680, iova=10245279744, write=1) at ../hw/virtio/vhost.c:1013 #1 0x0000559ffff9ac31 in vhost_backend_handle_iotlb_msg ( imsg=0x7ffddcfd32c0, dev=0x55a0012f6680) at ../hw/virtio/vhost-backend.c:411 #2 vhost_backend_handle_iotlb_msg (dev=dev@entry=0x55a0012f6680, imsg=imsg@entry=0x7ffddcfd32c0) at ../hw/virtio/vhost-backend.c:404 #3 0x0000559fffeded7b in slave_read (opaque=0x55a0012f6680) at ../hw/virtio/vhost-user.c:1464 #4 0x000055a0000c541b in aio_dispatch_handler ( ctx=ctx@entry=0x55a0010a2120, node=0x55a0012d9e00) at ../util/aio-posix.c:329 Fixes: 020e571b8b ("vhost: rework IOTLB messaging") Signed-off-by: Eugenio Pérez Message-Id: <20210129090728.831208-1-eperezma@redhat.com> Acked-by: Jason Wang Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/vhost-backend.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'hw/virtio') diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c index 222bbcc62d..31b33bde37 100644 --- a/hw/virtio/vhost-backend.c +++ b/hw/virtio/vhost-backend.c @@ -406,6 +406,11 @@ int vhost_backend_handle_iotlb_msg(struct vhost_dev *dev, { int ret = 0; + if (unlikely(!dev->vdev)) { + error_report("Unexpected IOTLB message when virtio device is stopped"); + return -EINVAL; + } + switch (imsg->type) { case VHOST_IOTLB_MISS: ret = vhost_device_iotlb_miss(dev, imsg->iova, -- cgit v1.2.3-55-g7522