netdev - Re: [PATCH net v2] ppp: ensure file->private

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Message-Id: <20160316.193904.361799863419478191.davem@davemloft.net>
Date:	Wed, 16 Mar 2016 19:39:04 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	g.nault@...halink.fr
Cc:	netdev@...r.kernel.org, paulus@...ba.org, alan@...ux.intel.com
Subject: Re: [PATCH net v2] ppp: ensure file->private_data can't be
 overridden

From: Guillaume Nault <g.nault@...halink.fr>
Date: Mon, 14 Mar 2016 21:17:16 +0100

> Locking ppp_mutex must be done before dereferencing file->private_data,
> otherwise it could be modified before ppp_unattached_ioctl() takes the
> lock. This could lead ppp_unattached_ioctl() to override ->private_data,
> thus leaking reference to the ppp_file previously pointed to.
> 
> v2: lock all ppp_ioctl() instead of just checking private_data in
>     ppp_unattached_ioctl(), to avoid ambiguous behaviour.
> 
> Fixes: f3ff8a4d80e8 ("ppp: push BKL down into the driver")
> Signed-off-by: Guillaume Nault <g.nault@...halink.fr>

Applied and queued up for -stable, thanks!