From f393808dc64149ccd0e5a8427505ba2974a59854 Mon Sep 17 00:00:00 2001 From: Vasily Khoruzhick Date: Thu, 25 Oct 2018 12:15:43 -0700 Subject: [PATCH] netfilter: conntrack: fix calculation of next bucket number in early_drop If there's no entry to drop in bucket that corresponds to the hash, early_drop() should look for it in other buckets. But since it increments hash instead of bucket number, it actually looks in the same bucket 8 times: hsize is 16k by default (14 bits) and hash is 32-bit value, so reciprocal_scale(hash, hsize) returns the same value for hash..hash+7 in most cases. Fix it by increasing bucket number instead of hash and rename _hash to bucket to avoid future confusion. Fixes: 3e86638e9a0b ("netfilter: conntrack: consider ct netns in early_drop logic") Cc: # v4.7+ Signed-off-by: Vasily Khoruzhick Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_core.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index ca1168d67fac..e92e749aff53 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1073,19 +1073,22 @@ static unsigned int early_drop_list(struct net *net, return drops; } -static noinline int early_drop(struct net *net, unsigned int _hash) +static noinline int early_drop(struct net *net, unsigned int hash) { - unsigned int i; + unsigned int i, bucket; for (i = 0; i < NF_CT_EVICTION_RANGE; i++) { struct hlist_nulls_head *ct_hash; - unsigned int hash, hsize, drops; + unsigned int hsize, drops; rcu_read_lock(); nf_conntrack_get_ht(&ct_hash, &hsize); - hash = reciprocal_scale(_hash++, hsize); + if (!i) + bucket = reciprocal_scale(hash, hsize); + else + bucket = (bucket + 1) % hsize; - drops = early_drop_list(net, &ct_hash[hash]); + drops = early_drop_list(net, &ct_hash[bucket]); rcu_read_unlock(); if (drops) { -- 2.30.2