netdev - Re: [v4.12 regression] netns: NULL deref in fib_sync_down

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Date:   Fri, 28 Jul 2017 20:36:02 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [v4.12 regression] netns: NULL deref in fib_sync_down_dev()

On Fri, Jul 28, 2017 at 10:28:16AM -0700, Cong Wang wrote:
> On Fri, Jul 28, 2017 at 9:43 AM, Ido Schimmel <idosch@...sch.org> wrote:
> > On Fri, Jul 28, 2017 at 06:00:47PM +0200, Michał Mirosław wrote:
> >> Dear NetDevs,
> >>
> >> Before I go to bisecting, have you seen a following NULL dereference,
> >> yet?  Where should I start looking?  It is triggered by deleting netns
> >> (cut-down script attached - triggers every time).  This was working
> >> correctly under v4.11.x.
> >
> > Thanks for the report. I just reproduced this on my system. I believe
> > the problem is a missing NULL check for 'in_dev' in
> > call_fib_nh_notifiers(). I'll test a fix.
> 
> But your commit 982acb97560c8118c2109504a22b0d78a580547d
> is merged in v4.11-rc1. How could 4.11.x work correctly?

It doesn't. I just reproduced this on v4.11.