linux-kernel - Re: [PATCH] IPVS: replace sprintf to snprintf to avoid stack buffer overflow

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Message-ID: <4BBDC008.2050306@trash.net>
Date:	Thu, 08 Apr 2010 13:37:44 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Simon Horman <horms@...ge.net.au>
CC:	wzt.wzt@...il.com, linux-kernel@...r.kernel.org,
	Wensong Zhang <wensong@...ux-vs.org>,
	Julian Anastasov <ja@....bg>, netdev@...r.kernel.org,
	lvs-devel@...r.kernel.org
Subject: Re: [PATCH] IPVS: replace sprintf to snprintf to avoid stack buffer
 overflow

Simon Horman wrote:
> On Wed, Apr 07, 2010 at 06:09:54PM +0200, Patrick McHardy wrote:
>> Simon Horman wrote:
>>> On Tue, Apr 06, 2010 at 10:50:20AM +0800, wzt.wzt@...il.com wrote:
>>>> IPVS not check the length of pp->name, use sprintf will cause stack buffer overflow.
>>>> struct ip_vs_protocol{} declare name as char *, if register a protocol as:
>>>> struct ip_vs_protocol ip_vs_test = {
>>>>         .name =			"aaaaaaaa....128...aaa",
>>>> 	.debug_packet =         ip_vs_tcpudp_debug_packet,
>>>> };
>>>>
>>>> when called ip_vs_tcpudp_debug_packet(), sprintf(buf, "%s TRUNCATED", pp->name); 
>>>> will cause stack buffer overflow.
>>>>
>>>> Signed-off-by: Zhitong Wang <zhitong.wangzt@...baba-inc.com>
>>> I think that the simple answer is, don't do that.
>> Indeed.
>>
>>> But your patch seems entirely reasonable to me.
>>>
>>> Acked-by: Simon Horman <horms@...ge.net.au>
>>>
>>> Patrick, please consider merging this.
>> I think this fix is a bit silly, we can simply print the name in
>> the pr_debug() statement and avoid both the potential overflow
>> and truncation.
>>
>> How does this look?
> 
> Looks good to me:
> 
> Acked-by: Simon Horman <horms@...ge.net.au>

Thanks, I've applied the patch.
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