Upstream-Status: Backport Supplementary fix of CVE-2016-5403 which is backported from: http://git.qemu.org/?p=qemu.git;a=commit;h=4b7f91e Signed-off-by: Kai Kang --- From 4b7f91ed0270a371e1933efa21ba600b6da23ab9 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 7 Sep 2016 11:51:25 -0400 Subject: [PATCH] virtio: zero vq->inuse in virtio_reset() vq->inuse must be zeroed upon device reset like most other virtqueue fields. In theory, virtio_reset() just needs assert(vq->inuse == 0) since devices must clean up in-flight requests during reset (requests cannot not be leaked!). In practice, it is difficult to achieve vq->inuse == 0 across reset because balloon, blk, 9p, etc implement various different strategies for cleaning up requests. Most devices call g_free(elem) directly without telling virtio.c that the VirtQueueElement is cleaned up. Therefore vq->inuse is not decremented during reset. This patch zeroes vq->inuse and trusts that devices are not leaking VirtQueueElements across reset. I will send a follow-up series that refactors request life-cycle across all devices and converts vq->inuse = 0 into assert(vq->inuse == 0) but this more invasive approach is not appropriate for stable trees. Signed-off-by: Stefan Hajnoczi Cc: qemu-stable Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Ladi Prosek --- hw/virtio/virtio.c | 1 + 1 file changed, 1 insertion(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 74c085c..e8a13a5 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -822,6 +822,7 @@ void virtio_reset(void *opaque) vdev->vq[i].signalled_used_valid = false; vdev->vq[i].notification = true; vdev->vq[i].vring.num = vdev->vq[i].vring.num_default; + vdev->vq[i].inuse = 0; } } -- 2.9.3