diff options
author | Liping Zhang <zlpnobody@gmail.com> | 2017-03-25 08:53:12 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-08 10:26:09 +0200 |
commit | 146561a3f1c8d7f9ef9b77964c846da48c62a6ac (patch) | |
tree | 159980e69318a370bffa92bc31814013b9592b1a /net/netfilter/nfnetlink_cttimeout.c | |
parent | 07b653405e3ad2a9f4ff8e654898a72069fbc27a (diff) |
netfilter: invoke synchronize_rcu after set the _hook_ to NULL
[ Upstream commit 3b7dabf029478bb80507a6c4500ca94132a2bc0b ]
Otherwise, another CPU may access the invalid pointer. For example:
CPU0 CPU1
- rcu_read_lock();
- pfunc = _hook_;
_hook_ = NULL; -
mod unload -
- pfunc(); // invalid, panic
- rcu_read_unlock();
So we must call synchronize_rcu() to wait the rcu reader to finish.
Also note, in nf_nat_snmp_basic_fini, synchronize_rcu() will be invoked
by later nf_conntrack_helper_unregister, but I'm inclined to add a
explicit synchronize_rcu after set the nf_nat_snmp_hook to NULL. Depend
on such obscure assumptions is not a good idea.
Last, in nfnetlink_cttimeout, we use kfree_rcu to free the time object,
so in cttimeout_exit, invoking rcu_barrier() is not necessary at all,
remove it too.
Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/netfilter/nfnetlink_cttimeout.c')
-rw-r--r-- | net/netfilter/nfnetlink_cttimeout.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index 139e0867e56e..47d6656c9119 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -646,8 +646,8 @@ static void __exit cttimeout_exit(void) #ifdef CONFIG_NF_CONNTRACK_TIMEOUT RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL); RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL); + synchronize_rcu(); #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ - rcu_barrier(); } module_init(cttimeout_init); |