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);
|