ACK: [natty, natty/ti-omap4 CVE 1/1] igmp: Avoid zero delay when receiving odd mixture of IGMP queries

[Stefan Bader]

On 23.01.2012 17:47, Andy Whitcroft wrote:
> From: Ben Hutchings <ben at decadent.org.uk>
> 
> Commit 5b7c84066733c5dfb0e4016d939757b38de189e4 ('ipv4: correct IGMP
> behavior on v3 query during v2-compatibility mode') added yet another
> case for query parsing, which can result in max_delay = 0.  Substitute
> a value of 1, as in the usual v3 case.
> 
> Reported-by: Simon McVittie <smcv at debian.org>
> References: http://bugs.debian.org/654876
> Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> 
> (cherry picked from commit a8c1f65c79cbbb2f7da782d4c9d15639a9b94b27)
> CVE-2012-0207
> BugLink: http://bugs.launchpad.net/bugs/917848
> Signed-off-by: Andy Whitcroft <apw at canonical.com>
> ---
>  net/ipv4/igmp.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index d9d5130..f574cf6 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -892,6 +892,8 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb,
>  		 * to be intended in a v3 query.
>  		 */
>  		max_delay = IGMPV3_MRC(ih3->code)*(HZ/IGMP_TIMER_SCALE);
> +		if (!max_delay)
> +			max_delay = 1;	/* can't mod w/ 0 */
>  	} else { /* v3 */
>  		if (!pskb_may_pull(skb, sizeof(struct igmpv3_query)))
>  			return;