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

From: Cliff Albert (cliff@oisec.net)
Date: Sat May 05 2001 - 02:32:39 EDT

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In reply to: David S. Miller: "[PATCH] (was Re: 2.4.4 & IPv6 oopses)"
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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!

-- 
Cliff Albert		| IRCNet:    #linux.nl, #ne2000, #linux, #freebsd.nl
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Next message: John R Lenton: "Re: REVISED: Experimentation with Athlon and fast_page_copy"
Previous message: Rick Hohensee: "Re: inserting a Forth-like language into the Linux kernel"
In reply to: David S. Miller: "[PATCH] (was Re: 2.4.4 & IPv6 oopses)"
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