From 8d8890b7751387f58ce0a6428773de2fbc0fd596 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Mon, 22 Jun 2009 14:14:41 +0200 Subject: netfilter: nf_conntrack: fix conntrack lookup race The RCU protected conntrack hash lookup only checks whether the entry has a refcount of zero to decide whether it is stale. This is not sufficient, entries are explicitly removed while there is at least one reference left, possibly more. Explicitly check whether the entry has been marked as dying to fix this. Signed-off-by: Patrick McHardy --- net/netfilter/nf_conntrack_core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index b0b06c7a948..7508f11c5b3 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -335,7 +335,8 @@ begin: h = __nf_conntrack_find(net, tuple); if (h) { ct = nf_ct_tuplehash_to_ctrack(h); - if (unlikely(!atomic_inc_not_zero(&ct->ct_general.use))) + if (unlikely(nf_ct_is_dying(ct) || + !atomic_inc_not_zero(&ct->ct_general.use))) h = NULL; else { if (unlikely(!nf_ct_tuple_equal(tuple, &h->tuple))) { @@ -510,7 +511,8 @@ static noinline int early_drop(struct net *net, unsigned int hash) cnt++; } - if (ct && unlikely(!atomic_inc_not_zero(&ct->ct_general.use))) + if (ct && unlikely(nf_ct_is_dying(ct) || + !atomic_inc_not_zero(&ct->ct_general.use))) ct = NULL; if (ct || cnt >= NF_CT_EVICTION_RANGE) break; -- cgit v1.2.3