From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59206) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eK6Pc-0004Tf-NP for qemu-devel@nongnu.org; Wed, 29 Nov 2017 12:44:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eK6Pa-0001XG-RE for qemu-devel@nongnu.org; Wed, 29 Nov 2017 12:44:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33590) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eK6Pa-0001Wj-LI for qemu-devel@nongnu.org; Wed, 29 Nov 2017 12:44:42 -0500 From: P J P Date: Wed, 29 Nov 2017 23:14:27 +0530 Message-Id: <20171129174428.27548-2-ppandit@redhat.com> In-Reply-To: <20171129174428.27548-1-ppandit@redhat.com> References: <20171129174428.27548-1-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH v4 1/2] virtio: check VirtQueue Vring object is set List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu Developers Cc: Cornelia Huck , Stefan Hajnoczi , zhangboxian , Paolo Bonzini , Prasad J Pandit From: Prasad J Pandit A guest could attempt to use an uninitialised VirtQueue object or unset Vring.align leading to a arithmetic exception. Add check to avoid it. Reported-by: Zhangboxian Signed-off-by: Prasad J Pandit --- hw/virtio/virtio.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) Update: removed !desc and !vring.align check from virtio_queue_set_rings -> https://lists.gnu.org/archive/html/qemu-devel/2017-11/msg04809.html diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 5884ce3480..a0d2c887cc 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -182,7 +182,7 @@ void virtio_queue_update_rings(VirtIODevice *vdev, int n) { VRing *vring = &vdev->vq[n].vring; - if (!vring->desc) { + if (!vring->num || !vring->desc || !vring->align) { /* not yet setup -> nothing to do */ return; } @@ -1414,6 +1414,9 @@ void virtio_config_modern_writel(VirtIODevice *vdev, void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr) { + if (!vdev->vq[n].vring.num) { + return; + } vdev->vq[n].vring.desc = addr; virtio_queue_update_rings(vdev, n); } @@ -1426,6 +1429,9 @@ hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n) void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc, hwaddr avail, hwaddr used) { + if (!vdev->vq[n].vring.num) { + return; + } vdev->vq[n].vring.desc = desc; vdev->vq[n].vring.avail = avail; vdev->vq[n].vring.used = used; @@ -1494,8 +1500,10 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align) */ assert(k->has_variable_vring_alignment); - vdev->vq[n].vring.align = align; - virtio_queue_update_rings(vdev, n); + if (align) { + vdev->vq[n].vring.align = align; + virtio_queue_update_rings(vdev, n); + } } static bool virtio_queue_notify_aio_vq(VirtQueue *vq) -- 2.13.6