linux-kernel - Re: [PATCH] batman-adv: fix potential NULL pointer dereferencing

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Message-ID: <541FE80B.7090108@meshcoding.com>
Date:	Mon, 22 Sep 2014 11:12:43 +0200
From:	Antonio Quartulli <antonio@...hcoding.com>
To:	mpirker@...ux.com,
	"mareklindner@...mailbox.ch" <mareklindner@...mailbox.ch>,
	"sw@...onwunderlich.de" <sw@...onwunderlich.de>,
	"davem@...emloft.net" <davem@...emloft.net>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] batman-adv: fix potential NULL pointer dereferencing



On 22/09/14 11:11, Mario Pirker wrote:
> From b451e7317148e18bf6c5c8fd747d79ab34260354 Mon Sep 17 00:00:00 2001
> From: Mario Pirker <mario.pirker@...logg.ox.ac.uk>
> Date: Tue, 16 Sep 2014 17:55:13 +0200
> Subject: [PATCH] batman-adv: fix potential NULL pointer dereferencing
> 
> The call batadv_gw_node_get may return NULL. The return value has to
> be sanity checked before the pointer is dereferenced.
> 
> Signed-off-by: Mario Pirker <mariopirker@...mail.com>
> ---

We already have a patch queued to fix this issue
(http://permalink.gmane.org/gmane.org.freifunk.batman/12357).

Actually it is not about a missing check but it is more about a typo in
the check right below the one you added.

Cheers,

>  net/batman-adv/gateway_client.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
> index 90cff58..7ee0913 100644
> --- a/net/batman-adv/gateway_client.c
> +++ b/net/batman-adv/gateway_client.c
> @@ -810,6 +810,11 @@ bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
>                 goto out;
>  
>         gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
> +
> +       /* gw_node can be NULL. We need to check before dereferencing */
> +       if (gw_node == NULL)
> +               goto out;
> +
>         if (!gw_node->bandwidth_down == 0)
>                 goto out;
>  
> -- 
> 1.8.1.4 		 	   		  
> 

-- 
Antonio Quartulli


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