From: Patrick McHardy <kaber@trash.net>
Date: Mon, 14 Feb 2011 16:35:07 +0000 (+0100)
Subject: netfilter: nf_iterate: fix incorrect RCU usage
X-Git-Tag: v2.6.38-rc6~20^2~19^2
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=de9963f0f2dfad128b26ae7bf6005f5948416a6d

netfilter: nf_iterate: fix incorrect RCU usage

As noticed by Eric, nf_iterate doesn't use RCU correctly by
accessing the prev pointer of a RCU protected list element when
a verdict of NF_REPEAT is issued.

Fix by jumping backwards to the hook invocation directly instead
of loading the previous list element before continuing the list
iteration.

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
---

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 32fcbe290c04..4aa614b8a96a 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -133,6 +133,7 @@ unsigned int nf_iterate(struct list_head *head,
 
 		/* Optimization: we don't need to hold module
 		   reference here, since function can't sleep. --RR */
+repeat:
 		verdict = elem->hook(hook, skb, indev, outdev, okfn);
 		if (verdict != NF_ACCEPT) {
 #ifdef CONFIG_NETFILTER_DEBUG
@@ -145,7 +146,7 @@ unsigned int nf_iterate(struct list_head *head,
 #endif
 			if (verdict != NF_REPEAT)
 				return verdict;
-			*i = (*i)->prev;
+			goto repeat;
 		}
 	}
 	return NF_ACCEPT;