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From:   Matteo Croce <mcroce@redhat.com>
Date:   Sat, 29 Jun 2019 21:39:39 +0200
Message-ID: <CAGnkfhzmGbeQe7L55nEv575XyubWqCLz=7NQPpH+TajDkkDiXg@mail.gmail.com>
Subject: Re: net: check before dereferencing netdev_ops during busy poll
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Josh Elsasser <jelsasser@appneta.com>,
        Sasha Levin <sashal@kernel.org>, stable@vger.kernel.org,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        David Miller <davem@davemloft.net>
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On Sat, Jun 29, 2019 at 9:45 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Jun 28, 2019 at 07:03:01PM -0700, Josh Elsasser wrote:
> > On Jun 28, 2019, at 3:55 PM, Sasha Levin <sashal@kernel.org> wrote:
> >
> > > What's the upstream commit id?
> >
> > The commit wasn't needed upstream, as I only sent the original patch after
> > 79e7fff47b7b ("net: remove support for per driver ndo_busy_poll()") had
> > made the fix unnecessary in Linus' tree.
> >
> > May've gotten lost in the shuffle due to my poor Fixes tags. The patch in
> > question applied only on top of the 4.9 stable release at the time, but the
> > actual NPE had been around in some form since 3.11 / 0602129286705 ("net: add
> > low latency socket poll").
>
> Ok, can people then resend this and be very explicit as to why this is
> needed only in a stable kernel tree and get reviews from people agreeing
> that this really is the correct fix?
>
> thanks,
>
> greg k-h

Hi Greg,

I think that David alredy reviewed the patch here:

https://lore.kernel.org/netdev/20180313.105115.682846171057663636.davem@davemloft.net/

Anyway, I tested the patch and it fixes the panic, at least on my
iwlwifi card, so:

Tested-by: Matteo Croce <mcroce@redhat.com>

Regards,
-- 
Matteo Croce
per aspera ad upstream