From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57514) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YVzl8-0003Ux-Kt for qemu-devel@nongnu.org; Thu, 12 Mar 2015 05:50:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YVzl5-0000f8-Te for qemu-devel@nongnu.org; Thu, 12 Mar 2015 05:50:30 -0400 From: Jason Wang Date: Thu, 12 Mar 2015 17:50:18 +0800 Message-Id: <1426153818-28804-1-git-send-email-jasowang@redhat.com> Subject: [Qemu-devel] [PATCH V2] virtio: validate the existence of handle_output before calling it List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Jason Wang , qemu-stable@nongnu.org, dkoch@verizon.com, "Michael S. Tsirkin" We don't validate the existence of handle_output which may let a buggy guest to trigger a SIGSEV easily. E.g: 1) write 10 to queue_sel to a virtio net device with only 1 queue 2) setup an arbitrary pfn 3) then notify queue 10 Fixing this by validating the existence of handle_output before. Cc: qemu-stable@nongnu.org Cc: Michael S. Tsirkin Signed-off-by: Jason Wang --- Changes from V1: - check the existence of both vring.desc and handle_output in the same line - describe the reproducer in the commit log --- hw/virtio/virtio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 3c6e430..17c1260 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -759,8 +759,9 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align) void virtio_queue_notify_vq(VirtQueue *vq) { - if (vq->vring.desc) { + if (vq->vring.desc && vq->handle_output) { VirtIODevice *vdev = vq->vdev; + trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); vq->handle_output(vdev, vq); } -- 2.1.0