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| author | Joerg Marx <joerg.marx@secunet.com> | 2010-05-20 15:55:30 +0200 |
|---|---|---|
| committer | Patrick McHardy <kaber@trash.net> | 2010-05-20 15:55:30 +0200 |
| commit | fc350777c705a39a312728ac5e8a6f164a828f5d (patch) | |
| tree | 62aa121cd62e416a505d35de9b5d77ab8ae89f66 | |
| parent | a1d7c1b4b8dfbc5ecadcff9284d64bb6ad4c0196 (diff) | |
| download | kernel_samsung_smdk4412-fc350777c705a39a312728ac5e8a6f164a828f5d.zip kernel_samsung_smdk4412-fc350777c705a39a312728ac5e8a6f164a828f5d.tar.gz kernel_samsung_smdk4412-fc350777c705a39a312728ac5e8a6f164a828f5d.tar.bz2 | |
netfilter: nf_conntrack: fix a race in __nf_conntrack_confirm against nf_ct_get_next_corpse()
This race was triggered by a 'conntrack -F' command running in parallel
to the insertion of a hash for a new connection. Losing this race led to
a dead conntrack entry effectively blocking traffic for a particular
connection until timeout or flushing the conntrack hashes again.
Now the check for an already dying connection is done inside the lock.
Signed-off-by: Joerg Marx <joerg.marx@secunet.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
| -rw-r--r-- | include/net/netfilter/nf_conntrack_core.h | 2 | ||||
| -rw-r--r-- | net/netfilter/nf_conntrack_core.c | 10 |
2 files changed, 11 insertions, 1 deletions
diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h index dffde8e..3d7524f 100644 --- a/include/net/netfilter/nf_conntrack_core.h +++ b/include/net/netfilter/nf_conntrack_core.h @@ -61,7 +61,7 @@ static inline int nf_conntrack_confirm(struct sk_buff *skb) int ret = NF_ACCEPT; if (ct && ct != &nf_conntrack_untracked) { - if (!nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct)) + if (!nf_ct_is_confirmed(ct)) ret = __nf_conntrack_confirm(skb); if (likely(ret == NF_ACCEPT)) nf_ct_deliver_cached_events(ct); diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index b83c530..eeeb8bc 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -424,6 +424,16 @@ __nf_conntrack_confirm(struct sk_buff *skb) spin_lock_bh(&nf_conntrack_lock); + /* We have to check the DYING flag inside the lock to prevent + a race against nf_ct_get_next_corpse() possibly called from + user context, else we insert an already 'dead' hash, blocking + further use of that particular connection -JM */ + + if (unlikely(nf_ct_is_dying(ct))) { + spin_unlock_bh(&nf_conntrack_lock); + return NF_ACCEPT; + } + /* See if there's one in the list already, including reverse: NAT could have grabbed it without realizing, since we're not in the hash. If there is, we lost race. */ |