diff options
| author | Florian Westphal <fw@strlen.de> | 2023-05-04 14:55:02 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2023-05-10 08:50:39 +0200 |
| commit | e72eeab542dbf4f544e389e64fa13b82a1b6d003 (patch) | |
| tree | 296f5202317f6d23f41818b9454d4ce0215e7bdb /net | |
| parent | dc1c9fd4a8bbe1e06add9053010b652449bfe411 (diff) | |
netfilter: conntrack: fix possible bug_on with enable_hooks=1
I received a bug report (no reproducer so far) where we trip over
712 rcu_read_lock();
713 ct_hook = rcu_dereference(nf_ct_hook);
714 BUG_ON(ct_hook == NULL); // here
In nf_conntrack_destroy().
First turn this BUG_ON into a WARN. I think it was triggered
via enable_hooks=1 flag.
When this flag is turned on, the conntrack hooks are registered
before nf_ct_hook pointer gets assigned.
This opens a short window where packets enter the conntrack machinery,
can have skb->_nfct set up and a subsequent kfree_skb might occur
before nf_ct_hook is set.
Call nf_conntrack_init_end() to set nf_ct_hook before we register the
pernet ops.
Fixes: ba3fbe663635 ("netfilter: nf_conntrack: provide modparam to always register conntrack hooks")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/core.c | 6 | ||||
| -rw-r--r-- | net/netfilter/nf_conntrack_standalone.c | 3 |
2 files changed, 6 insertions, 3 deletions
diff --git a/net/netfilter/core.c b/net/netfilter/core.c index f0783e42108b..5f76ae86a656 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -711,9 +711,11 @@ void nf_conntrack_destroy(struct nf_conntrack *nfct) rcu_read_lock(); ct_hook = rcu_dereference(nf_ct_hook); - BUG_ON(ct_hook == NULL); - ct_hook->destroy(nfct); + if (ct_hook) + ct_hook->destroy(nfct); rcu_read_unlock(); + + WARN_ON(!ct_hook); } EXPORT_SYMBOL(nf_conntrack_destroy); diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index 57f6724c99a7..169e16fc2bce 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -1218,11 +1218,12 @@ static int __init nf_conntrack_standalone_init(void) nf_conntrack_htable_size_user = nf_conntrack_htable_size; #endif + nf_conntrack_init_end(); + ret = register_pernet_subsys(&nf_conntrack_net_ops); if (ret < 0) goto out_pernet; - nf_conntrack_init_end(); return 0; out_pernet: |