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authorPatrick McHardy <kaber@trash.net>2009-06-22 14:14:41 +0200
committerPatrick McHardy <kaber@trash.net>2009-06-22 14:14:41 +0200
commit8d8890b7751387f58ce0a6428773de2fbc0fd596 (patch)
tree651b2f1da674823f386d4ba9165a6d81212e52cf
parent5c8ec910e789a92229978d8fd1fce7b62e8ac711 (diff)
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 <kaber@trash.net>
-rw-r--r--net/netfilter/nf_conntrack_core.c6
1 files changed, 4 insertions, 2 deletions
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;