netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation

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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: 6c5d5cfbe3 ("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>

...

This commit is contained in:

Cong Wang 2018-02-07 21:59:17 -08:00 • committed by Pablo Neira Ayuso

parent fd2c19b2a2

commit b3e456fce9

1 changed files with 6 additions and 6 deletions

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net/ipv4/netfilter/ipt_CLUSTERIP.c

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