# Re: \[PATCH\]\[MCAST\]IPv6: Check packet size when process Multicast Address and Source Specific Query

- From: YOSHIFUJI Hideaki / 吉藤英明 \<hidden\>
- Date: 2005-10-31 05:27:15 
- List: netdev
- Page: https://ratatoskr.run/netdev/2005/10/776898
- Thread: https://ratatoskr.run/netdev/2005/10/776895/t.md

```text
In article [ref] (at Mon, 31 Oct 2005 13:20:21 +0800), Yan Zheng [ref] says:

> 
> Signed-off-by: Yan Zheng <redacted>
> 
> Index: net/ipv6/mcast.c
> ================================================================================
> --- linux-2.6.14/net/ipv6/mcast.c	2005-10-30 23:09:33.000000000 +0800
> +++ linux/net/ipv6/mcast.c	2005-10-31 13:13:10.000000000 +0800
> @@ -1156,7 +1156,12 @@ int igmp6_event_query(struct sk_buff *sk
>  			return 0;
>  		}
>  		/* mark sources to include, if group & source-specific */
> -		mark = mlh2->nsrcs != 0;
> +		if (mlh2->nsrcs != 0) {
> +			if (!pskb_may_pull(skb, mlh2->nsrcs * sizeof(struct in6_addr) +
> +				(sizeof(struct mld2_query) - sizeof(struct icmp6hdr))))
> +				return -EINVAL;
> +			mark = 1;
> +		}
>  	} else {
>  		in6_dev_put(idev);
>  		return -EINVAL;

You cannot continue using mlh2, local copy of skb->h.raw
after pskb_may_pull(). Please refresh it.

--yoshfuji
```