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 <p...@fedoraproject.org> >>>> >>>> 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 <luodalon...@gmail.com> >>>> Signed-off-by: Prasad J Pandit <p...@fedoraproject.org> >>>> --- >>>> 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