linux-kernel - Re: [PATCH] net/ethoc: fix null dereference on error exit path

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Message-ID: <20160522194228.GA11011@octofox.metropolis>
Date:	Sun, 22 May 2016 22:42:28 +0300
From:	Max Filippov <jcmvbkbc@...il.com>
To:	Colin King <colin.king@...onical.com>
Cc:	"David S . Miller" <davem@...emloft.net>,
	Andrew Lunn <andrew@...n.ch>,
	Florian Fainelli <f.fainelli@...il.com>,
	Tobias Klauser <tklauser@...tanz.ch>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net/ethoc: fix null dereference on error exit path

Hi Colin,

On Sun, May 22, 2016 at 08:08:18PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> priv is assigned to NULL however all the error exit paths to label 'free'
> dereference priv, causing a null pointer dereference.
> 
> Examination of the code shows that all error exits via the 'free'
> label path occur before priv is assigned to netdev_priv(netdev), hence
> there is no need to call clk_disable_unprepare and so the location of
> the label should be moved to free_netdev statement to avoid this null
> dereference on priv.

This description is a bit inaccurate. Indeed all 'goto free' above the
'priv = netdev_priv(netdev);' need to skip 'if (priv->clk)' check, but
there are two more 'goto free' below that line, and they look correct
now, but after this patch they'll leave the clock enabled.

-- 
Thanks.
-- Max