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

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Message-ID: <20100407223445.GA15810@verge.net.au>
Date:	Thu, 8 Apr 2010 08:34:46 +1000
From:	Simon Horman <horms@...ge.net.au>
To:	Patrick McHardy <kaber@...sh.net>
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

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>

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