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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2018-02-08 06:59:17 +0100 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-02-08 13:54:20 +0100 |
| commit | b3e456fce9f51d6276e576d00271e2813c1b8b67 (patch) | |
| tree | bf1504e9cf6429f33ab2be0381f975d5caf27c42 /net | |
| parent | netfilter: x_tables: remove size check (diff) | |
| download | linux-b3e456fce9f51d6276e576d00271e2813c1b8b67.tar.xz linux-b3e456fce9f51d6276e576d00271e2813c1b8b67.zip | |
netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/netfilter/ipt_CLUSTERIP.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index 3a84a60f6b39..1ff72b87a066 100644 --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -107,12 +107,6 @@ clusterip_config_entry_put(struct net *net, struct clusterip_config *c) 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 *net, struct clusterip_config *c) 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(); |