[PATCH v2] net: fix NULL pointer reference in cipso_v4_doi_free

[Paul Moore]

On Mon, Aug 30, 2021 at 12:45 PM Jakub Kicinski <kuba at kernel.org> wrote:
> On Mon, 30 Aug 2021 10:17:05 -0400 Paul Moore wrote:
> > On Mon, Aug 30, 2021 at 6:28 AM 王贇 <yun.wang at linux.alibaba.com> wrote:
> > >
> > > In netlbl_cipsov4_add_std() when 'doi_def->map.std' alloc
> > > failed, we sometime observe panic:
> > >
> > >   BUG: kernel NULL pointer dereference, address:
> > >   ...
> > >   RIP: 0010:cipso_v4_doi_free+0x3a/0x80
> > >   ...
> > >   Call Trace:
> > >    netlbl_cipsov4_add_std+0xf4/0x8c0
> > >    netlbl_cipsov4_add+0x13f/0x1b0
> > >    genl_family_rcv_msg_doit.isra.15+0x132/0x170
> > >    genl_rcv_msg+0x125/0x240
> > >
> > > This is because in cipso_v4_doi_free() there is no check
> > > on 'doi_def->map.std' when doi_def->type got value 1, which
> > > is possibe, since netlbl_cipsov4_add_std() haven't initialize
> > > it before alloc 'doi_def->map.std'.
> > >
> > > This patch just add the check to prevent panic happen in similar
> > > cases.
> > >
> > > Reported-by: Abaci <abaci at linux.alibaba.com>
> > > Signed-off-by: Michael Wang <yun.wang at linux.alibaba.com>
> > > ---
> > >  net/netlabel/netlabel_cipso_v4.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > I see this was already merged, but it looks good to me, thanks for
> > making those changes.
>
> FWIW it looks like v1 was also merged:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=733c99ee8b

Yeah, that is unfortunate, there was a brief discussion about that
over on one of the -stable patches for the v1 patch (odd that I never
saw a patchbot post for the v1 patch?).  Having both merged should be
harmless, but we want to revert the v1 patch as soon as we can.
Michael, can you take care of this?

-- 
paul moore
www.paul-moore.com