netdev - Re: [PATCH net-next v4 2/9] net: filter: keep original BPF program around

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Message-Id: <20140913.170506.851550533823976026.davem@davemloft.net>
Date:	Sat, 13 Sep 2014 17:05:06 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	dborkman@...hat.com
Cc:	eric.dumazet@...il.com, ast@...mgrid.com, netdev@...r.kernel.org,
	xemul@...allels.com
Subject: Re: [PATCH net-next v4 2/9] net: filter: keep original BPF program
 around

From: Daniel Borkmann <dborkman@...hat.com>
Date: Fri, 12 Sep 2014 08:09:31 +0200

>> [PATCH] net: filter: fix possible use after free
>>
>> If kmemdup() fails, we free fp->orig_prog and return -ENOMEM
>>
>> sk_attach_filter()
>>   -> sk_filter_uncharge(sk, fp)
>>    -> sk_filter_release(fp)
>>     -> call_rcu(&fp->rcu, sk_filter_release_rcu)
>>      -> sk_filter_release_rcu()
>>       -> sk_release_orig_filter()
>>          fprog = fp->orig_prog; // not NULL, but points to freed memory
>> 	  kfree(fprog->filter); // use after free, potential corruption
>>            kfree(fprog); // double free or corruption
>>
>> Note: This was fixed in 3.17+ with commit 278571baca2a
>> ("net: filter: simplify socket charging")
>>
>> Found by AddressSanitizer
>>
>> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
>> Fixes: a3ea269b8bcdb ("net: filter: keep original BPF program around")
> 
> Thanks Eric!
> 
> Acked-by: Daniel Borkmann <dborkman@...hat.com>

Queued up for -stable, thanks.
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