Re: [PATCH net] igmp: Avoid zero delay when receiving odd mixture of IGMP queries

[Ben Hutchings <ben@decadent.org.uk>]

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On Mon, 2012-01-09 at 22:04 +0000, Ben Hutchings wrote:
> 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.

This has been assigned CVE-2012-0207.

Ben.

> Reported-by: Simon McVittie <smcv@debian.org>
> References: http://bugs.debian.org/654876
> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> ---
>  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 d577199..e0d42db 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -875,6 +875,8 @@ 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;

-- 
Ben Hutchings
Life is what happens to you while you're busy making other plans.
                                                               - John Lennon

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