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

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Date:	Mon, 19 Sep 2011 16:32:48 +0800
From:	Rongqing Li <rongqing.li@...driver.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	<netdev@...r.kernel.org>
Subject: Re: [PATCH 1/1] snmp6 relevant data structures are freed twice.

On 09/19/2011 04:29 PM, Eric Dumazet wrote:
> 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>
>
>
>

Ok, I will resend it.

-- 
Best Reagrds,
Roy | RongQing Li
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