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List:       linux-netdev
Subject:    Re: [PATCH][IPv6]: Fix incorrect length check in rawv6_sendmsg()
From:       Sridhar Samudrala <sri () us ! ibm ! com>
Date:       2007-03-30 17:47:04
Message-ID: 1175276825.23146.1.camel () w-sridhar2 ! beaverton ! ibm ! com
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On Fri, 2007-03-30 at 09:13 +0900, YOSHIFUJI Hideaki / 吉藤英明 wrote:
> In article <20070329.142644.70222545.davem@davemloft.net> (at Thu, 29 Mar 2007 \
> 14:26:44 -0700 (PDT)), David Miller <davem@davemloft.net> says: 
> > From: Sridhar Samudrala <sri@us.ibm.com>
> > Date: Thu, 29 Mar 2007 14:17:28 -0700
> > 
> > > The check for length in rawv6_sendmsg() is incorrect.
> > > As len is an unsigned int, (len < 0) will never be TRUE.
> > > I think checking for IPV6_MAXPLEN(65535) is better.
> > > 
> > > Is it possible to send ipv6 jumbo packets using raw
> > > sockets? If so, we can remove this check.
> > 
> > I don't see why such a limitation against jumbo would exist,
> > does anyone else?
> > 
> > Thanks for catching this Sridhar.  A good compiler should simply
> > fail to compile "if (x < 0)" when 'x' is an unsigned type, don't
> > you think :-)
> 
> Dave, we use "int" for returning value,
> so we should fix this anyway, IMHO;
> we should not allow len > INT_MAX.
> 
> Don't you think so?
> 
> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

Acked-by: Sridhar Samudrala <sri@us.ibm.com>

> 
> diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
> index 306d5d8..203e069 100644
> --- a/net/ipv6/raw.c
> +++ b/net/ipv6/raw.c
> @@ -687,9 +687,9 @@ static int rawv6_sendmsg(struct kiocb *iocb, struct sock *sk,
> 	int err;
> 
> 	/* Rough check on arithmetic overflow,
> -	   better check is made in ip6_build_xmit
> +	   better check is made in ip6_append_data().
> 	 */
> -	if (len < 0)
> +	if (len > INT_MAX)
> 		return -EMSGSIZE;
> 
> 	/* Mirror BSD error message compatibility */
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 0ad4719..f590db5 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -615,7 +615,7 @@ do_udp_sendmsg:
> 		return udp_sendmsg(iocb, sk, msg, len);
> 
> 	/* Rough check on arithmetic overflow,
> -	   better check is made in ip6_build_xmit
> +	   better check is made in ip6_append_data().
> 	   */
> 	if (len > INT_MAX - sizeof(struct udphdr))
> 		return -EMSGSIZE;
> 
> --yoshfuji
> -
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