[NETFILTER]: conntrack: fix {nf,ip}_ct_iterate_cleanup endless loops Fix {nf,ip}_ct_iterate_cleanup unconfirmed list handling: - unconfirmed entries can not be killed manually, they are removed on confirmation or final destruction of the conntrack entry, which means we might iterate forever without making forward progress. This can happen in combination with the conntrack event cache, which holds a reference to the conntrack entry, which is only released when the packet makes it all the way through the stack or a different packet is handled. - taking references to an unconfirmed entry and using it outside the locked section doesn't work, the list entries are not refcounted and another CPU might already be waiting to destroy the entry What the code really wants to do is make sure the references of the hash table to the selected conntrack entries are released, so they will be destroyed once all references from skbs and the event cache are dropped. Since unconfirmed entries haven't even entered the hash yet, simply mark them as dying and skip confirmation based on that. Signed-off-by: Patrick McHardy --- commit 841de8621862a5406d2a236dd142a5e5db167d25 tree 347d137f0d6466f0b4da83256bfbeaa4150f105a parent 8d1117a9f5d302d8d460fbe7ef322b382e45c9ce author Patrick McHardy Mon, 26 Feb 2007 18:48:05 +0100 committer Patrick McHardy Wed, 28 Feb 2007 19:02:00 +0100 include/linux/netfilter_ipv4/ip_conntrack_core.h | 2 +- include/net/netfilter/nf_conntrack_core.h | 2 +- net/ipv4/netfilter/ip_conntrack_core.c | 2 +- net/netfilter/nf_conntrack_core.c | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/netfilter_ipv4/ip_conntrack_core.h b/include/linux/netfilter_ipv4/ip_conntrack_core.h index 907d4f5..e3a6df0 100644 --- a/include/linux/netfilter_ipv4/ip_conntrack_core.h +++ b/include/linux/netfilter_ipv4/ip_conntrack_core.h @@ -45,7 +45,7 @@ static inline int ip_conntrack_confirm(s int ret = NF_ACCEPT; if (ct) { - if (!is_confirmed(ct)) + if (!is_confirmed(ct) && !is_dying(ct)) ret = __ip_conntrack_confirm(pskb); ip_ct_deliver_cached_events(ct); } diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h index 7fdc72c..85634e1 100644 --- a/include/net/netfilter/nf_conntrack_core.h +++ b/include/net/netfilter/nf_conntrack_core.h @@ -64,7 +64,7 @@ static inline int nf_conntrack_confirm(s int ret = NF_ACCEPT; if (ct) { - if (!nf_ct_is_confirmed(ct)) + if (!nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct)) ret = __nf_conntrack_confirm(pskb); nf_ct_deliver_cached_events(ct); } diff --git a/net/ipv4/netfilter/ip_conntrack_core.c b/net/ipv4/netfilter/ip_conntrack_core.c index 8556a4f..f8b3009 100644 --- a/net/ipv4/netfilter/ip_conntrack_core.c +++ b/net/ipv4/netfilter/ip_conntrack_core.c @@ -1242,7 +1242,7 @@ get_next_corpse(int (*iter)(struct ip_co list_for_each_entry(h, &unconfirmed, list) { ct = tuplehash_to_ctrack(h); if (iter(ct, data)) - goto found; + set_bit(IPS_DYING_BIT, &ct->status); } write_unlock_bh(&ip_conntrack_lock); return NULL; diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 9b02ec4..cb29ba7 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1052,7 +1052,7 @@ get_next_corpse(int (*iter)(struct nf_co list_for_each_entry(h, &unconfirmed, list) { ct = nf_ct_tuplehash_to_ctrack(h); if (iter(ct, data)) - goto found; + set_bit(IPS_DYING_BIT, &ct->status); } write_unlock_bh(&nf_conntrack_lock); return NULL;