Re: [PATCH] virtio_ring: fix KMSAN error for premapped mode

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jun 24, 2024 at 03:51:50PM +0200, Alexander Potapenko wrote:
> On Fri, Jun 7, 2024 at 8:34 AM Jason Wang <jasowang@redhat.com> wrote:
> >
> > On Thu, Jun 6, 2024 at 7:13 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
> > >
> > > Add kmsan for virtqueue_dma_map_single_attrs to fix:
> > >
> > > BUG: KMSAN: uninit-value in receive_buf+0x45ca/0x6990
> > >  receive_buf+0x45ca/0x6990
> > >  virtnet_poll+0x17e0/0x3130
> > >  net_rx_action+0x832/0x26e0
> > >  handle_softirqs+0x330/0x10f0
> > >  [...]
> > >
> > > Uninit was created at:
> > >  __alloc_pages_noprof+0x62a/0xe60
> > >  alloc_pages_noprof+0x392/0x830
> > >  skb_page_frag_refill+0x21a/0x5c0
> > >  virtnet_rq_alloc+0x50/0x1500
> > >  try_fill_recv+0x372/0x54c0
> > >  virtnet_open+0x210/0xbe0
> > >  __dev_open+0x56e/0x920
> > >  __dev_change_flags+0x39c/0x2000
> > >  dev_change_flags+0xaa/0x200
> > >  do_setlink+0x197a/0x7420
> > >  rtnl_setlink+0x77c/0x860
> > >  [...]
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > Tested-by: Alexander Potapenko <glider@google.com>
> >
> > Acked-by: Jason Wang <jasowang@redhat.com>
> 
> Jason, Michael, any chance this patch can make it to 6.10?
> The bug in question has essentially been blocking KMSAN on syzbot for
> the past month:
> https://syzkaller.appspot.com/bug?id=2819883f3d376b703e686e700fde00a01eec62fa
> 
> The patch should probably have
>   Fixes: b6253b4e21939 ("virtio_ring: introduce dma map api for virtqueue")
> 
> , but I am not exactly sure why syzkaller only started triggering the
> bug this year, given that the patch dates back to 2023.

Yes that's probably a good idea. I will queue it with this tag.

-- 
MST