From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56874) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bm2UI-00007h-7S for qemu-devel@nongnu.org; Mon, 19 Sep 2016 13:36:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bm2Jy-0007GB-9v for qemu-devel@nongnu.org; Mon, 19 Sep 2016 13:25:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55716) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bm2Jy-0007Fo-0b for qemu-devel@nongnu.org; Mon, 19 Sep 2016 13:25:34 -0400 References: <1474275971-3546-1-git-send-email-ppandit@redhat.com> <20160919155555.GB26238@stefanha-x1.localdomain> <11a29d88-2e4d-d016-6a44-de5d7c6cbe57@redhat.com> From: Laszlo Ersek Message-ID: <5117e2fb-2658-dbb7-cbdd-e8fe9ee14880@redhat.com> Date: Mon, 19 Sep 2016 19:25:29 +0200 MIME-Version: 1.0 In-Reply-To: <11a29d88-2e4d-d016-6a44-de5d7c6cbe57@redhat.com> Content-Type: text/plain; charset=utf-8 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: Laurent Vivier , Stefan Hajnoczi , P J P Cc: Qemu Developers , Qinghao Tang , "Michael S. Tsirkin" , Prasad J Pandit , Peter Maydell On 09/19/16 19:16, Laurent Vivier wrote: > > > On 19/09/2016 18:59, Laszlo Ersek wrote: >> 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. >>> > > Laszlo, it seems Peter (and some others) would prefer to use exit(1) > instead of exit(EXIT_FAILURE), so I don't think my series will be applied. Thanks for the information, Laurent! Prasad, can you please send a v3 then, to address Stefan's feedback? Thank you Laszlo