From: Xin Long <lucien.xin@xxxxxxxxx>
[ Upstream commit d5494acb88aa9dd1325079c9b8855008a52c19b3 ]
Now dccp_ipv4 works as a kernel module. During loading this module, if
one dccp packet is being recieved after inet_add_protocol but before
register_pernet_subsys in which v4_ctl_sk is initialized, a null pointer
dereference may be triggered because of init_net.dccp.v4_ctl_sk is 0x0.
Jianlin found this issue when the following call trace occurred:
[ 171.950177] BUG: unable to handle kernel NULL pointer dereference at 0000000000000110
[ 171.951007] IP: [<ffffffffc0558364>] dccp_v4_ctl_send_reset+0xc4/0x220 [dccp_ipv4]
[...]
[ 171.984629] Call Trace:
[ 171.984859] <IRQ>
[ 171.985061]
[ 171.985213] [<ffffffffc0559a53>] dccp_v4_rcv+0x383/0x3f9 [dccp_ipv4]
[ 171.985711] [<ffffffff815ca054>] ip_local_deliver_finish+0xb4/0x1f0
[ 171.986309] [<ffffffff815ca339>] ip_local_deliver+0x59/0xd0
[ 171.986852] [<ffffffff810cd7a4>] ? update_curr+0x104/0x190
[ 171.986956] [<ffffffff815c9cda>] ip_rcv_finish+0x8a/0x350
[ 171.986956] [<ffffffff815ca666>] ip_rcv+0x2b6/0x410
[ 171.986956] [<ffffffff810c83b4>] ? task_cputime+0x44/0x80
[ 171.986956] [<ffffffff81586f22>] __netif_receive_skb_core+0x572/0x7c0
[ 171.986956] [<ffffffff810d2c51>] ? trigger_load_balance+0x61/0x1e0
[ 171.986956] [<ffffffff81587188>] __netif_receive_skb+0x18/0x60
[ 171.986956] [<ffffffff8158841e>] process_backlog+0xae/0x180
[ 171.986956] [<ffffffff8158799d>] net_rx_action+0x16d/0x380
[ 171.986956] [<ffffffff81090b7f>] __do_softirq+0xef/0x280
[ 171.986956] [<ffffffff816b6a1c>] call_softirq+0x1c/0x30
This patch is to move inet_add_protocol after register_pernet_subsys in
dccp_v4_init, so that v4_ctl_sk is initialized before any incoming dccp
packets are processed.
Reported-by: Jianlin Shi <jishi@xxxxxxxxxx>
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
net/dccp/ipv4.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 502d9a885329..adce7f5d4f07 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -1051,33 +1051,34 @@ static int __init dccp_v4_init(void)
{
int err = proto_register(&dccp_v4_prot, 1);
- if (err != 0)
+ if (err)
goto out;
- err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
- if (err != 0)
- goto out_proto_unregister;
-
inet_register_protosw(&dccp_v4_protosw);
err = register_pernet_subsys(&dccp_v4_ops);
if (err)
goto out_destroy_ctl_sock;
+
+ err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
+ if (err)
+ goto out_proto_unregister;
+
out:
return err;
+out_proto_unregister:
+ unregister_pernet_subsys(&dccp_v4_ops);
out_destroy_ctl_sock:
inet_unregister_protosw(&dccp_v4_protosw);
- inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
-out_proto_unregister:
proto_unregister(&dccp_v4_prot);
goto out;
}
static void __exit dccp_v4_exit(void)
{
+ inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
unregister_pernet_subsys(&dccp_v4_ops);
inet_unregister_protosw(&dccp_v4_protosw);
- inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
proto_unregister(&dccp_v4_prot);
}
--
2.15.1