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netfilter: expect: add to hash table after expect init

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assuming we have lockless readers we should make sure they can only
see expectations that have already been initialized.

hlist_add_head_rcu acts as memory barrier, move it after timer setup.

Theoretically we could crash due to a del_timer() on other cpu
seeing garbage data.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2017-07-10 15:06:39 +02:00 committed by Pablo Neira Ayuso
parent 7a68ada6ec
commit 56a97e701c
1 changed files with 6 additions and 6 deletions
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12
net/netfilter/nf_conntrack_expect.c
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@ -368,12 +368,6 @@ static void nf_ct_expect_insert(struct nf_conntrack_expect *exp)
/* two references : one for hash insert, one for the timer */ /* two references : one for hash insert, one for the timer */
refcount_add(2, &exp->use); refcount_add(2, &exp->use);
hlist_add_head_rcu(&exp->lnode, &master_help->expectations);
master_help->expecting[exp->class]++;
hlist_add_head_rcu(&exp->hnode, &nf_ct_expect_hash[h]);
net->ct.expect_count++;
setup_timer(&exp->timeout, nf_ct_expectation_timed_out, setup_timer(&exp->timeout, nf_ct_expectation_timed_out,
(unsigned long)exp); (unsigned long)exp);
helper = rcu_dereference_protected(master_help->helper, helper = rcu_dereference_protected(master_help->helper,
@ -384,6 +378,12 @@ static void nf_ct_expect_insert(struct nf_conntrack_expect *exp)
} }
add_timer(&exp->timeout); add_timer(&exp->timeout);
hlist_add_head_rcu(&exp->lnode, &master_help->expectations);
master_help->expecting[exp->class]++;
hlist_add_head_rcu(&exp->hnode, &nf_ct_expect_hash[h]);
net->ct.expect_count++;
NF_CT_STAT_INC(net, expect_create); NF_CT_STAT_INC(net, expect_create);
} }