Re: [PATCH] (was Re: 2.4.4 & IPv6 oopses)

[Cliff Albert <cliff@oisec.net>]

On Fri, May 04, 2001 at 06:46:12PM -0700, David S. Miller wrote:

> Pekka Savola writes:
>  > struct in6_addr *saddr = NULL;
>  > [...]
>  >         if (skb && ipv6_chk_addr(&skb->nh.ipv6h->saddr, dev))
>  >                 saddr = &skb->nh.ipv6h->saddr;
>  > [...]
>  > 	ndisc_send_ns(dev, neigh, target, target, saddr);
>  > [...]
>  > This check apparently fails? and saddr is left null.
> 
> Yes, it can fail, and this is normal.  The problem is in
> ndisc_send_ns().
> 
>  > in ndisc_send_ns, NULL saddr is checked:
>  > 
>  > send_llinfo = dev->addr_len && ipv6_addr_type(saddr) != IPV6_ADDR_ANY;
>  > 
>  > which make a null ptr dereference.  send_llinfo check was added recently
>  > to fix RFC incompliancy a week or so ago.
> 
> A few lines later we setup saddr properly if it is NULL, what we need
> to do is either:
> 
> 1) Move that "if (saddr == NULL)" code block up above the send_llinfo
>    check.
> 
>    I think this would break the thing the send_llinfo check
>    was meant to fix, but I can't be sure.
> 
> 2) Just check for NULL saddr in the send_llinfo check and if NULL
>    then send_llinfo is set to zero.
> 
> For now, I've put solution #2 into my tree, patch attached below.
> 
> --- linux/net/ipv6/ndisc.c.~1~	Thu May  3 00:01:10 2001
> +++ linux/net/ipv6/ndisc.c	Fri May  4 18:44:54 2001
> @@ -382,7 +382,7 @@
>  	int send_llinfo;
>  
>  	len = sizeof(struct icmp6hdr) + sizeof(struct in6_addr);
> -	send_llinfo = dev->addr_len && ipv6_addr_type(saddr) != IPV6_ADDR_ANY;
> +	send_llinfo = dev->addr_len && saddr && ipv6_addr_type(saddr) != IPV6_ADDR_ANY;
>  	if (send_llinfo)
>  		len += NDISC_OPT_SPACE(dev->addr_len);
>  

This patch fixed ALL my ICMPv6 related problems. Thanks!

-- 
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