netdev - Re: WARNING in xfrm_state

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Date:   Tue, 19 Jun 2018 14:28:32 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>
CC:     Jason Litzinger <jlitzingerdev@...il.com>,
        David Miller <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: WARNING in xfrm_state_fini (2)

On Mon, Jun 18, 2018 at 09:25:31AM +0200, Dmitry Vyukov wrote:
> On Mon, Jun 18, 2018 at 6:14 AM, Jason Litzinger
> <jlitzingerdev@...il.com> wrote:
> > I've simplified the reproducer provided by syzbot to the included
> > version.  The warning is reproduced 100% using the qemu image in the
> > syzkaller docs running the latest upstream and net.
> >
> > As noted on the dashboard, this is similar to [1], in that an entry
> > remains in the xfrm_state_walk list, but different because the
> > protocol is not 0, it is 43, IPPROTO_ROUTING (and is valid by the fix
> > for [1], see 6a53b7593233).
> >
> > Unfortunately, when a namespace exits, xfrm_state_fini only flushes
> > IPSEC protocols.  I don't have enough experience with the xfrm
> > subsystem to know whether this is correct, however, dc00a525603650a14
> > explicitly allows non ipsec protocols, as well as 0 for "all".
> >
> > Would it be more appropriate for flush to also flush the non ipsec
> > protocols allowed in xfrm_user.c:validate_tmpl (explicitly or with 0)?
> >
> > If someone with more experience with the subsystem believes that to be
> > the case I'm happy to send a patch (against net or ipsec?), otherwise
> > I'm going to keep digging to see if a better option presents itself.
> >
> > Regardless I hope the simplified reproducer might be useful.
> >
> > -Jason
> >
> > [1]
> > https://syzkaller.appspot.com/bug?id=c922592229951800c197ce48a5eaab8877c33723
> >
> > * I wasn't subscribed to the list for the original message, so I'm
> >   using the GUI to reply...apologies if anything is mangled.
> 
> +kernel developers back to CC

Thanks for the info!

I'm traveling currently, so it may take some time
until I can look at it.