calipso: fix memory leak in netlbl_calipso_add_pass()

If IPv6 support is disabled at boot (ipv6.disable=1),
the calipso_init() -> netlbl_calipso_ops_register() function isn't called,
and the netlbl_calipso_ops_get() function always returns NULL.
In this case, the netlbl_calipso_add_pass() function allocates memory
for the doi_def variable but doesn't free it with the calipso_doi_free().

BUG: memory leak
unreferenced object 0xffff888011d68180 (size 64):
  comm "syz-executor.1", pid 10746, jiffies 4295410986 (age 17.928s)
  hex dump (first 32 bytes):
    00 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<...>] kmalloc include/linux/slab.h:552 [inline]
    [<...>] netlbl_calipso_add_pass net/netlabel/netlabel_calipso.c:76 [inline]
    [<...>] netlbl_calipso_add+0x22e/0x4f0 net/netlabel/netlabel_calipso.c:111
    [<...>] genl_family_rcv_msg_doit+0x22f/0x330 net/netlink/genetlink.c:739
    [<...>] genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
    [<...>] genl_rcv_msg+0x341/0x5a0 net/netlink/genetlink.c:800
    [<...>] netlink_rcv_skb+0x14d/0x440 net/netlink/af_netlink.c:2515
    [<...>] genl_rcv+0x29/0x40 net/netlink/genetlink.c:811
    [<...>] netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
    [<...>] netlink_unicast+0x54b/0x800 net/netlink/af_netlink.c:1339
    [<...>] netlink_sendmsg+0x90a/0xdf0 net/netlink/af_netlink.c:1934
    [<...>] sock_sendmsg_nosec net/socket.c:651 [inline]
    [<...>] sock_sendmsg+0x157/0x190 net/socket.c:671
    [<...>] ____sys_sendmsg+0x712/0x870 net/socket.c:2342
    [<...>] ___sys_sendmsg+0xf8/0x170 net/socket.c:2396
    [<...>] __sys_sendmsg+0xea/0x1b0 net/socket.c:2429
    [<...>] do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46
    [<...>] entry_SYSCALL_64_after_hwframe+0x61/0xc6

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with Syzkaller

Fixes: cb72d38 ("netlabel: Initial support for the CALIPSO netlink protocol.")
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
[PM: merged via the LSM tree at Jakub Kicinski request]
Signed-off-by: Paul Moore <paul@paul-moore.com>

Author: Gavrilov Ilia

net/netlabel/netlabel_calipso.c

@@ -54,6 +54,28 @@ static const struct nla_policy calipso_genl_policy[NLBL_CALIPSO_A_MAX + 1] = {
 	[NLBL_CALIPSO_A_MTYPE] = { .type = NLA_U32 },
 };
 
+static const struct netlbl_calipso_ops *calipso_ops;
+
+/**
+ * netlbl_calipso_ops_register - Register the CALIPSO operations
+ * @ops: ops to register
+ *
+ * Description:
+ * Register the CALIPSO packet engine operations.
+ *
+ */
+const struct netlbl_calipso_ops *
+netlbl_calipso_ops_register(const struct netlbl_calipso_ops *ops)
+{
+	return xchg(&calipso_ops, ops);
+}
+EXPORT_SYMBOL(netlbl_calipso_ops_register);
+
+static const struct netlbl_calipso_ops *netlbl_calipso_ops_get(void)
+{
+	return READ_ONCE(calipso_ops);
+}
+
 /* NetLabel Command Handlers
  */
 /**
@@ -96,15 +118,18 @@ static int netlbl_calipso_add_pass(struct genl_info *info,
  *
  */
 static int netlbl_calipso_add(struct sk_buff *skb, struct genl_info *info)
-
 {
 	int ret_val = -EINVAL;
 	struct netlbl_audit audit_info;
+	const struct netlbl_calipso_ops *ops = netlbl_calipso_ops_get();
 
 	if (!info->attrs[NLBL_CALIPSO_A_DOI] ||
 	    !info->attrs[NLBL_CALIPSO_A_MTYPE])
 		return -EINVAL;
 
+	if (!ops)
+		return -EOPNOTSUPP;
+
 	netlbl_netlink_auditinfo(&audit_info);
 	switch (nla_get_u32(info->attrs[NLBL_CALIPSO_A_MTYPE])) {
 	case CALIPSO_MAP_PASS:
@@ -363,28 +388,6 @@ int __init netlbl_calipso_genl_init(void)
 	return genl_register_family(&netlbl_calipso_gnl_family);
 }
 
-static const struct netlbl_calipso_ops *calipso_ops;
-
-/**
- * netlbl_calipso_ops_register - Register the CALIPSO operations
- * @ops: ops to register
- *
- * Description:
- * Register the CALIPSO packet engine operations.
- *
- */
-const struct netlbl_calipso_ops *
-netlbl_calipso_ops_register(const struct netlbl_calipso_ops *ops)
-{
-	return xchg(&calipso_ops, ops);
-}
-EXPORT_SYMBOL(netlbl_calipso_ops_register);
-
-static const struct netlbl_calipso_ops *netlbl_calipso_ops_get(void)
-{
-	return READ_ONCE(calipso_ops);
-}
-
 /**
  * calipso_doi_add - Add a new DOI to the CALIPSO protocol engine
  * @doi_def: the DOI structure