From: Patrick McHardy <kaber@xxxxxxxxx>
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@xxxxxxxxx>
Acked-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
net/netfilter/core.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 32fcbe2..4aa614b 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;
--
1.7.2.3
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