nfnetlink_log_init registers netlink callback nfulnl_rcv_nl_event before
registering the pernet_subsys, but the callback relies on data structures
allocated by pernet init functions.
When nfnetlink_log is loaded, if a netlink message is received after
the netlink callback is registered but before the pernet_subsys is
registered, the kernel will panic in the sequence
nfulnl_rcv_nl_event
nfnl_log_pernet
net_generic
BUG_ON(id == 0) where id is nfnl_log_net_id.
The panic can be easily reproduced in 4.0.3 by:
while true ;do modprobe nfnetlink_log ; rmmod nfnetlink_log ; done &
while true ;do ip netns add dummy ; ip netns del dummy ; done &
This patch moves register_pernet_subsys to earlier in nfnetlink_log_init.
Notice that the BUG_ON hit in 4.0.3 was recently removed in 2591ffd308
["netns: remove BUG_ONs from net_generic()"].
Signed-off-by: Francesco Ruggeri <fruggeri@xxxxxxxxxx>
---
net/netfilter/nfnetlink_log.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index 3ad9126..536ced5 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -1075,6 +1075,12 @@ static int __init nfnetlink_log_init(void)
{
int status = -ENOMEM;
+ status = register_pernet_subsys(&nfnl_log_net_ops);
+ if (status < 0) {
+ pr_err("failed to register pernet ops\n");
+ goto out;
+ }
+
netlink_register_notifier(&nfulnl_rtnl_notifier);
status = nfnetlink_subsys_register(&nfulnl_subsys);
if (status < 0) {
@@ -1088,28 +1094,23 @@ static int __init nfnetlink_log_init(void)
goto cleanup_subsys;
}
- status = register_pernet_subsys(&nfnl_log_net_ops);
- if (status < 0) {
- pr_err("failed to register pernet ops\n");
- goto cleanup_logger;
- }
return status;
-cleanup_logger:
- nf_log_unregister(&nfulnl_logger);
cleanup_subsys:
nfnetlink_subsys_unregister(&nfulnl_subsys);
cleanup_netlink_notifier:
netlink_unregister_notifier(&nfulnl_rtnl_notifier);
+ unregister_pernet_subsys(&nfnl_log_net_ops);
+out:
return status;
}
static void __exit nfnetlink_log_fini(void)
{
- unregister_pernet_subsys(&nfnl_log_net_ops);
nf_log_unregister(&nfulnl_logger);
nfnetlink_subsys_unregister(&nfulnl_subsys);
netlink_unregister_notifier(&nfulnl_rtnl_notifier);
+ unregister_pernet_subsys(&nfnl_log_net_ops);
}
MODULE_DESCRIPTION("netfilter userspace logging");
--
1.8.1.4
--
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