From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44549) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bm1us-0004rt-R8 for qemu-devel@nongnu.org; Mon, 19 Sep 2016 12:59:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bm1uo-00063d-Rc for qemu-devel@nongnu.org; Mon, 19 Sep 2016 12:59:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52066) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bm1uo-00063F-ML for qemu-devel@nongnu.org; Mon, 19 Sep 2016 12:59:34 -0400 References: <1474275971-3546-1-git-send-email-ppandit@redhat.com> <20160919155555.GB26238@stefanha-x1.localdomain> From: Laszlo Ersek Message-ID: Date: Mon, 19 Sep 2016 18:59:31 +0200 MIME-Version: 1.0 In-Reply-To: <20160919155555.GB26238@stefanha-x1.localdomain> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [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: Stefan Hajnoczi , P J P Cc: Qemu Developers , Qinghao Tang , "Michael S. Tsirkin" , Prasad J Pandit , Laurent Vivier On 09/19/16 17:55, Stefan Hajnoczi wrote: > On Mon, Sep 19, 2016 at 02:36:11PM +0530, P J P wrote: >> 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); > > exit(1) is used everywhere else in the file (including just a few lines > above in the same function). Please use exit(1) for consistency. Laurent's pending series [Qemu-devel] [PATCH 00/26] trivial: use exit(EXIT_SUCCESS) and exit(EXIT_FAILURE) specifically his patch [Qemu-devel] [PATCH 11/26] pci, virtio: use exit(EXIT_SUCCESS) and exit(EXIT_FAILURE) converts the argument of the exit() that you name to EXIT_FAILURE. So using EXIT_FAILURE in Prasad's patch is actually what will uphold consistency. > Looks fine otherwise. > Thanks! Laszlo