Commit f393808d authored by Vasily Khoruzhick's avatar Vasily Khoruzhick Committed by Pablo Neira Ayuso
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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: 3e86638e

 ("netfilter: conntrack: consider ct netns in early_drop logic")
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: default avatarVasily Khoruzhick <vasilykh@arista.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent e4844c9c
...@@ -1073,19 +1073,22 @@ static unsigned int early_drop_list(struct net *net, ...@@ -1073,19 +1073,22 @@ static unsigned int early_drop_list(struct net *net,
return drops; 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++) { for (i = 0; i < NF_CT_EVICTION_RANGE; i++) {
struct hlist_nulls_head *ct_hash; struct hlist_nulls_head *ct_hash;
unsigned int hash, hsize, drops; unsigned int hsize, drops;
rcu_read_lock(); rcu_read_lock();
nf_conntrack_get_ht(&ct_hash, &hsize); 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(); rcu_read_unlock();
if (drops) { if (drops) {
......
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