The "already exists" dedup logic in __nf_conncount_add() decides whether a connection has already been counted and can be skipped instead of incrementing the connlimit count. It compares the conntrack zone of a list entry with the zone of the connection being added using nf_ct_zone_id() and nf_ct_zone_equal(), passing conn->zone.dir or zone->dir as the direction argument. Those helpers take enum ip_conntrack_dir values: IP_CT_DIR_ORIGINAL is 0 and IP_CT_DIR_REPLY is 1. However, zone->dir is a u8 bitmask: NF_CT_ZONE_DIR_ORIG is 1, NF_CT_ZONE_DIR_REPL is 2 and NF_CT_DEFAULT_ZONE_DIR is 3. Passing that bitmask as the enum direction shifts the meaning of every non-zero value. An ORIG-only zone passes 1 and is tested as REPLY, while REPL-only and default zones pass 2 or 3 and test bits beyond the valid direction range. In those cases nf_ct_zone_id() can fall back to NF_CT_DEFAULT_ZONE_ID instead of using the real zone id, so different zones can be treated as equal and dedup collapses to tuple equality alone. nf_conncount stores and compares the original-direction tuple for a connection. If an skb already has an attached conntrack entry, get_ct_or_tuple_from_skb() explicitly copies ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, regardless of the packet's ctinfo. Therefore the zone comparison in the tuple dedup path must use IP_CT_DIR_ORIGINAL as well; the zone direction bitmask describes where a zone id applies, not which direction this conncount tuple represents. Fix the two dedup comparisons by passing IP_CT_DIR_ORIGINAL directly. Do not special-case NF_CT_DEFAULT_ZONE_DIR and do not compare raw zone ids: using the existing helpers with IP_CT_DIR_ORIGINAL preserves the direction-aware NF_CT_DEFAULT_ZONE_ID fallback. A default bidirectional zone contains the ORIG bit, so it naturally returns the real zone id; reply-only zones continue to fall back for original-direction tuple comparisons. Fixes: 21ba8847f857 ("netfilter: nf_conncount: Fix garbage collection with zones") Fixes: b36e4523d4d5 ("netfilter: nf_conncount: fix garbage collection confirm race") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Yizhou Zhao --- Changes in v2: - Use IP_CT_DIR_ORIGINAL directly instead of adding a helper to map zone->dir to an enum direction, suggested by Florian Westphal. - Link to v1: https://lore.kernel.org/netfilter-devel/20260706114820.74006-1-zhaoyz24@mails.tsinghua.edu.cn/ --- diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c index 91582069f6d2..e9ea6d9466e7 100644 --- a/net/netfilter/nf_conncount.c +++ b/net/netfilter/nf_conncount.c @@ -211,8 +211,8 @@ static int __nf_conncount_add(struct net *net, /* Not found, but might be about to be confirmed */ if (PTR_ERR(found) == -EAGAIN) { if (nf_ct_tuple_equal(&conn->tuple, &tuple) && - nf_ct_zone_id(&conn->zone, conn->zone.dir) == - nf_ct_zone_id(zone, zone->dir)) + nf_ct_zone_id(&conn->zone, IP_CT_DIR_ORIGINAL) == + nf_ct_zone_id(zone, IP_CT_DIR_ORIGINAL)) goto out_put; /* already exists */ } else { collect++; @@ -223,7 +223,7 @@ static int __nf_conncount_add(struct net *net, found_ct = nf_ct_tuplehash_to_ctrack(found); if (nf_ct_tuple_equal(&conn->tuple, &tuple) && - nf_ct_zone_equal(found_ct, zone, zone->dir)) { + nf_ct_zone_equal(found_ct, zone, IP_CT_DIR_ORIGINAL)) { /* * We should not see tuples twice unless someone hooks * this into a table without "-p tcp --syn". -- 2.47.3