4.15-stable review patch. If anyone has any objections, please let me know.
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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();