| From b3e456fce9f51d6276e576d00271e2813c1b8b67 Mon Sep 17 00:00:00 2001 |
| From: Cong Wang <xiyou.wangcong@gmail.com> |
| Date: Wed, 7 Feb 2018 21:59:17 -0800 |
| Subject: netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation |
| |
| From: Cong Wang <xiyou.wangcong@gmail.com> |
| |
| commit b3e456fce9f51d6276e576d00271e2813c1b8b67 upstream. |
| |
| There is a race condition between clusterip_config_entry_put() |
| and clusterip_config_init(), after we release the spinlock in |
| clusterip_config_entry_put(), a new proc file with a same IP could |
| be created immediately since it is already removed from the configs |
| list, therefore it triggers this warning: |
| |
| ------------[ cut here ]------------ |
| proc_dir_entry 'ipt_CLUSTERIP/172.20.0.170' already registered |
| WARNING: CPU: 1 PID: 4152 at fs/proc/generic.c:330 proc_register+0x2a4/0x370 fs/proc/generic.c:329 |
| Kernel panic - not syncing: panic_on_warn set ... |
| |
| As a quick fix, just move the proc_remove() inside the spinlock. |
| |
| Reported-by: <syzbot+03218bcdba6aa76441a3@syzkaller.appspotmail.com> |
| Fixes: 6c5d5cfbe3c5 ("netfilter: ipt_CLUSTERIP: check duplicate config when initializing") |
| Tested-by: Paolo Abeni <pabeni@redhat.com> |
| Cc: Xin Long <lucien.xin@gmail.com> |
| Cc: Pablo Neira Ayuso <pablo@netfilter.org> |
| Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> |
| Reviewed-by: Xin Long <lucien.xin@gmail.com> |
| Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| net/ipv4/netfilter/ipt_CLUSTERIP.c | 12 ++++++------ |
| 1 file changed, 6 insertions(+), 6 deletions(-) |
| |
| --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c |
| +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c |
| @@ -107,12 +107,6 @@ clusterip_config_entry_put(struct net *n |
| |
| local_bh_disable(); |
| if (refcount_dec_and_lock(&c->entries, &cn->lock)) { |
| - list_del_rcu(&c->list); |
| - spin_unlock(&cn->lock); |
| - local_bh_enable(); |
| - |
| - unregister_netdevice_notifier(&c->notifier); |
| - |
| /* In case anyone still accesses the file, the open/close |
| * functions are also incrementing the refcount on their own, |
| * so it's safe to remove the entry even if it's in use. */ |
| @@ -120,6 +114,12 @@ clusterip_config_entry_put(struct net *n |
| if (cn->procdir) |
| proc_remove(c->pde); |
| #endif |
| + list_del_rcu(&c->list); |
| + spin_unlock(&cn->lock); |
| + local_bh_enable(); |
| + |
| + unregister_netdevice_notifier(&c->notifier); |
| + |
| return; |
| } |
| local_bh_enable(); |