net/smc: fix a memory leak in smc_sysctl_net_exit()

Recently added smc_sysctl_net_exit() forgot to free
the memory allocated from smc_sysctl_net_init()
for non initial network namespace.

Fixes: 462791bb ("net/smc: add sysctl interface for SMC")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Cc: Tony Lu <tonylu@linux.alibaba.com>
Cc: Dust Li <dust.li@linux.alibaba.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/smc/smc_sysctl.c

@@ -61,5 +61,10 @@ int __net_init smc_sysctl_net_init(struct net *net)
 
 void __net_exit smc_sysctl_net_exit(struct net *net)
 {
+	struct ctl_table *table;
+
+	table = net->smc.smc_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->smc.smc_hdr);
+	if (!net_eq(net, &init_net))
+		kfree(table);
 }