[PATCH 7/8] netfilter: nf_nat_snmp: Fix panic when snmp_trap_helper fails to register

[Pablo Neira Ayuso]

From: Gao Feng <f...@ikuai8.com>

In the commit 93557f53e1fb ("netfilter: nf_conntrack: nf_conntrack snmp
helper"), the snmp_helper is replaced by nf_nat_snmp_hook. So the
snmp_helper is never registered. But it still tries to unregister the
snmp_helper, it could cause the panic.

Now remove the useless snmp_helper and the unregister call in the
error handler.

Fixes: 93557f53e1fb ("netfilter: nf_conntrack: nf_conntrack snmp helper")
Signed-off-by: Gao Feng <f...@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 net/ipv4/netfilter/nf_nat_snmp_basic.c | 19 +------------------
 1 file changed, 1 insertion(+), 18 deletions(-)

diff --git a/net/ipv4/netfilter/nf_nat_snmp_basic.c 
b/net/ipv4/netfilter/nf_nat_snmp_basic.c
index 5a8f7c360887..53e49f5011d3 100644
--- a/net/ipv4/netfilter/nf_nat_snmp_basic.c
+++ b/net/ipv4/netfilter/nf_nat_snmp_basic.c
@@ -1260,16 +1260,6 @@ static const struct nf_conntrack_expect_policy 
snmp_exp_policy = {
        .timeout        = 180,
 };
 
-static struct nf_conntrack_helper snmp_helper __read_mostly = {
-       .me                     = THIS_MODULE,
-       .help                   = help,
-       .expect_policy          = &snmp_exp_policy,
-       .name                   = "snmp",
-       .tuple.src.l3num        = AF_INET,
-       .tuple.src.u.udp.port   = cpu_to_be16(SNMP_PORT),
-       .tuple.dst.protonum     = IPPROTO_UDP,
-};
-
 static struct nf_conntrack_helper snmp_trap_helper __read_mostly = {
        .me                     = THIS_MODULE,
        .help                   = help,
@@ -1288,17 +1278,10 @@ static struct nf_conntrack_helper snmp_trap_helper 
__read_mostly = {
 
 static int __init nf_nat_snmp_basic_init(void)
 {
-       int ret = 0;
-
        BUG_ON(nf_nat_snmp_hook != NULL);
        RCU_INIT_POINTER(nf_nat_snmp_hook, help);
 
-       ret = nf_conntrack_helper_register(&snmp_trap_helper);
-       if (ret < 0) {
-               nf_conntrack_helper_unregister(&snmp_helper);
-               return ret;
-       }
-       return ret;
+       return nf_conntrack_helper_register(&snmp_trap_helper);
 }
 
 static void __exit nf_nat_snmp_basic_fini(void)
-- 
2.1.4