Subject: Re: next-20151207 - crash in IPv6 code

From: Florian Westphal <[email-masked]>
Date: Tue, 8 Dec 2015 12:34:09 +0100

Valdis Kletnieks <[email-masked]> wrote:

[ CC Pablo ]

> Seen this in 2 boots out of two on next-20151207 when IPV6 networking
> was available.  It was stable when no net was available. Also, next-20161127 is OK.
> Haven't bisected it yet - this ring any bells?

Thanks for the report, my fault -- its caused by
029f7f3b8701cc7aca8bdb which is only in Pablos nf-next tree.

This should fix this bug (proper patch w. changelog coming
after more testing):

diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -441,11 +441,14 @@ nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *prev,  struct net_devic
 			return false;
 
 		fp->next = prev->next;
-		skb_queue_walk(head, iter) {
-			if (iter->next != prev)
-				continue;
-			iter->next = fp;
-			break;
+
+		iter = head;
+		while (iter) {
+			if (iter->next == prev) {
+				iter->next = fp;
+				break;
+			}
+			iter = iter->next;
 		}
 
 		skb_morph(prev, head);