Re: [PATCH] IPVS: replace sprintf to snprintf to avoid stack buffer over

To: Simon Horman <horms@xxxxxxxxxxxx>
Subject: Re: [PATCH] IPVS: replace sprintf to snprintf to avoid stack buffer overflow
Cc: wzt.wzt@xxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, Wensong Zhang <wensong@xxxxxxxxxxxx>, Julian Anastasov <ja@xxxxxx>, netdev@xxxxxxxxxxxxxxx, lvs-devel@xxxxxxxxxxxxxxx
From: Patrick McHardy <kaber@xxxxxxxxx>
Date: Thu, 08 Apr 2010 13:37:44 +0200
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@xxxxxxxxx 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 =                    "",
>>>>    .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@xxxxxxxxxxxxxxx>
>>> 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@xxxxxxxxxxxx>
>>> 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@xxxxxxxxxxxx>

Thanks, I've applied the patch.
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