netdev - Re: [PATCH] net: ipconfig: fix ic_close

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Message-Id: <20170327.210724.753199024787667111.davem@davemloft.net>
Date:   Mon, 27 Mar 2017 21:07:24 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     mark.rutland@....com
Cc:     linux-kernel@...r.kernel.org, kuznet@....inr.ac.ru,
        yoshfuji@...ux-ipv6.org, jmorris@...ei.org, kaber@...sh.net,
        netdev@...r.kernel.org
Subject: Re: [PATCH] net: ipconfig: fix ic_close_devs() use-after-free

From: Mark Rutland <mark.rutland@....com>
Date: Mon, 27 Mar 2017 18:00:14 +0100

> Our chosen ic_dev may be anywhere in our list of ic_devs, and we may
> free it before attempting to close others. When we compare d->dev and
> ic_dev->dev, we're potentially dereferencing memory returned to the
> allocator. This causes KASAN to scream for each subsequent ic_dev we
> check.
> 
> As there's a 1-1 mapping between ic_devs and netdevs, we can instead
> compare d and ic_dev directly, which implicitly handles the !ic_dev
> case, and avoids the use-after-free. The ic_dev pointer may be stale,
> but we will not dereference it.
> 
> Original splat:
 ...
> Signed-off-by: Mark Rutland <mark.rutland@....com>

Applied, thanks.