From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Bug in net/ipv6/ip6_fib.c:fib6_dump_table()
Date: Fri, 22 Jun 2012 20:13:05 +0200
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Cc: "davem@davemloft.net" <davem@davemloft.net>,
	"kaber@trash.net" <kaber@trash.net>,
	Debabrata Banerjee <dbavatar@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"yoshfuji@linux-ipv6.org" <yoshfuji@linux-ipv6.org>,
	"jmorris@namei.org" <jmorris@namei.org>,
	"pekkas@netcore.fi" <pekkas@netcore.fi>,
	"kuznet@ms2.inr.ac.ru" <kuznet@ms2.inr.ac.ru>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
To: Josh Hunt <johunt@akamai.com>
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On Fri, 2012-06-22 at 08:44 -0500, Josh Hunt wrote:

> Ahh. That makes sense and is what Alexey said before I just didn't put
> it all together. So we are OK reverting this patch? I cannot find a path
> where the walker's pointers are updated without the tb6_lock write_lock.
> 

There was a bug somewhere, not sure we want to NULL dereference again.

Following fix should at least avoid a never ending dump

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 74c21b9..6083276 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1349,8 +1349,8 @@ static int fib6_walk_continue(struct fib6_walker_t *w)
 			if (w->leaf && fn->fn_flags & RTN_RTINFO) {
 				int err;
 
-				if (w->count < w->skip) {
-					w->count++;
+				if (w->skip) {
+					w->skip--;
 					continue;
 				}