linux-kernel - Re: WARNING in xfrm_state

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Date:   Tue, 30 Jan 2018 13:22:13 -0800
From:   Eric Biggers <ebiggers3@...il.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Steffen Klassert <steffen.klassert@...unet.com>,
        syzbot 
        <bot+427f0a9138719ba183c0d37d8c2d070567f7761a@...kaller.appspotmail.com>,
        David Miller <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        syzkaller-bugs@...glegroups.com
Subject: Re: WARNING in xfrm_state_fini

On Mon, Nov 27, 2017 at 09:37:07AM -0800, Cong Wang wrote:
> On Mon, Nov 27, 2017 at 3:55 AM, Steffen Klassert
> <steffen.klassert@...unet.com> wrote:
> > On Tue, Nov 21, 2017 at 06:44:04PM -0800, Cong Wang wrote:
> >> User-space uses proto==0 as a wildcard, but xfrm_id_proto_match()
> >> doesn't consider it as a match with IPSEC_PROTO_ANY, in this case
> >> it should match all. Not sure if the following patch is the best way to
> >> fix it, or perhaps x->id.proto should be initialized to some of these 3
> >> values, but looking into ->init_temprop() it is not the case.
> >
> > x->id is copied from the policy template and it seems that we don't
> > validate the id of the template when inserting the policy. iproute2
> > checks for a valid IPsec proto but the kernel does not do so. I think
> > we should check the policy template and reject inserting if the proto
> > is invalid.
> >
> 
> Oh, I thought 0 is used as wildcard, so it is not.
> 
> Something like below?
> 
> @@ -1445,6 +1446,15 @@ static int validate_tmpl(int nr, struct
> xfrm_user_tmpl *ut, u16 family)
>                 default:
>                         return -EINVAL;
>                 }
> +               switch (ut[i].id.proto) {
> +               case IPPROTO_AH:
> +               case IPPROTO_ESP:
> +               case IPPROTO_COMP:
> +                       break;
> +               default:
> +                       return -EINVAL;
> +               }
> +
>         }
> 
>         return 0;
> 

I assume this is supposed to be fixed by the following, so marking it closed for
syzbot:

#syz fix: xfrm: check id proto in validate_tmpl()

But syzbot has been hitting a WARN_ON() in xfrm_state_fini() even after that
fix, so it should get reported as a new bug.