calipso: fix memory leak in netlbl_calipso_add_pass()

In the Linux kernel, the following vulnerability has been resolved:

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

[PM: merged via the LSM tree at Jakub Kicinski request]