netdev - Re: [PATCH 1/1] snmp6 relevant data structures are freed twice.

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Date:	Mon, 19 Sep 2011 10:29:49 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	rongqing.li@...driver.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH 1/1] snmp6 relevant data structures are freed twice.

Le lundi 19 septembre 2011 à 15:03 +0800, rongqing.li@...driver.com a
écrit :
> From: Roy.Li <rongqing.li@...driver.com>
> 
> When calling snmp6_alloc_dev fails, the snmp6 relevant memory
> are freed by snmp6_alloc_dev. Calling in6_dev_finish_destroy
> will free these memory twice.
> 
> Double free will lead that undefined behavior occurs.
> 
> Signed-off-by: Roy.Li <rongqing.li@...driver.com>
> ---
>  net/ipv6/addrconf.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 8f1e5be..ba01f72 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -374,8 +374,8 @@ static struct inet6_dev * ipv6_add_dev(struct net_device *dev)
>  			"%s(): cannot allocate memory for statistics; dev=%s.\n",
>  			__func__, dev->name));
>  		neigh_parms_release(&nd_tbl, ndev->nd_parms);
> -		ndev->dead = 1;
> -		in6_dev_finish_destroy(ndev);
> +		dev_put(dev);
> +		kfree(ndev);
>  		return NULL;
>  	}
>  

This seems a very old bug, and your fix applicable to old kernels as
well, thanks.

Could your patch title could be refined to the following ?

0) No need for the 1/1 suffix
1) include ipv6: prefix
2) change the message a bit, since normal operations are OK, only
failure and error recovery is buggy.

[PATCH] ipv6: fix a possible double free

Acked-by: Eric Dumazet <eric.dumazet@...il.com>


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