From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35198) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bluX0-0006D9-Qe for qemu-devel@nongnu.org; Mon, 19 Sep 2016 05:06:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bluWv-00034F-D2 for qemu-devel@nongnu.org; Mon, 19 Sep 2016 05:06:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38534) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bluWv-00032c-6P for qemu-devel@nongnu.org; Mon, 19 Sep 2016 05:06:25 -0400 From: P J P Date: Mon, 19 Sep 2016 14:36:11 +0530 Message-Id: <1474275971-3546-1-git-send-email-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH v2] virtio: add check for descriptor's mapped address List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu Developers Cc: Qinghao Tang , Laszlo Ersek , "Michael S. Tsirkin" , Stefan Hajnoczi , Prasad J Pandit From: Prasad J Pandit virtio back end uses set of buffers to facilitate I/O operations. If its size is too large, 'cpu_physical_memory_map' could return a null address. This would result in a null dereference while un-mapping descriptors. Add check to avoid it. Reported-by: Qinghao Tang Signed-off-by: Prasad J Pandit --- hw/virtio/virtio.c | 5 +++++ 1 file changed, 5 insertions(+) Update per: -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg03889.html diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 15ee3a7..311dd0b 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove } iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write); + if (!iov[num_sg].iov_base) { + error_report("virtio: bogus descriptor or out of resources"); + exit(EXIT_FAILURE); + } + iov[num_sg].iov_len = len; addr[num_sg] = pa; -- 2.5.5