Merge branch 'ipv6-blackhole-route-fix'

Martin KaFai Lau says:

====================
ipv6: Initialize rt6_info properly in ip6_blackhole_route()

This patchset ensures the rt6_info's fields are initialized properly
in ip6_blackhole_route() where xfrm_policy is the primarily user.
The first patch is a prep work.  The second patch is the fix.  It
fixes d52d3997f843 ("ipv6: Create percpu rt6_info").

Here is the oops reported by Phil Sutter <phil@nwl.cc>:

BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0
IP: [<ffffffff8171a95e>] __ip6_datagram_connect+0x71e/0xa20
PGD c2cb1067 PUD c2d7a067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
Modules linked in: cmac nfs lockd grace sunrpc bridge stp llc nvidia(PO) snd_usb_audio snd_usbmidi_lib iTCO_wdt
CPU: 1 PID: 2964 Comm: ping6 Tainted: P           O    4.2.1-aufs #10
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./4Core1333-Viiv, BIOS P1.60 07/01/2008
task: ffff8800ca62bc00 ti: ffff880129a14000 task.ti: ffff880129a14000
RIP: 0010:[<ffffffff8171a95e>]  [<ffffffff8171a95e>] __ip6_datagram_connect+0x71e/0xa20
RSP: 0018:ffff880129a17da8  EFLAGS: 00010296
RAX: 000000000000000b RBX: 0000000000000000 RCX: 0000000000000006
RDX: 0000000000000007 RSI: 0000000000000246 RDI: ffff88012fc8d5a0
RBP: ffff8800cb9a9048 R08: 756e207369207472 R09: 216c6c756e207369
R10: 0000000000000665 R11: 0000000000000006 R12: ffff8800cb9a8cf8
R13: ffff8800cb9a8cf8 R14: 0000000000000000 R15: ffff8800cb9a8cc0
FS:  00007fb76ad74700(0000) GS:ffff88012fc80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000000a0 CR3: 00000000c2dba000 CR4: 00000000000406e0
Stack:
 ffff8800cb9a9048 ffff8800cb9a8de0 ffff8800cb9feb70 ffffffff816b2c41
 00007fb70000000b ffffea0000df7200 ffff8800cb9f5cfc ffff8800cb9a8cc0
 03fffffffe068a20 ffff8800cb9a8cc0 ffffffff817097c0 0000000100000000
Call Trace:
 [<ffffffff816b2c41>] ? udp_lib_get_port+0x1a1/0x380
 [<ffffffff817097c0>] ? udpv6_rcv+0x20/0x20
 [<ffffffff8171ac82>] ? ip6_datagram_connect+0x22/0x40
 [<ffffffff8163ae9b>] ? SyS_connect+0x6b/0xb0
 [<ffffffff810767ac>] ? __do_page_fault+0x15c/0x380
 [<ffffffff8163a8d3>] ? SyS_socket+0x63/0xa0
 [<ffffffff81741957>] ? entry_SYSCALL_64_fastpath+0x12/0x6a
Code: ba ae 00 00 00 48 c7 c6 7b 71 94 81 48 c7 c7 63 71 94 81 e8 6c 0f 02 00 48 85 db 75 0e 48 c7 c7 9f 71 94 81 31 c0 e8 59 0f 02 00 <48> 83 bb a0 00 00 00 00 75 0e 48 c7 c7 ae 71 94 81 31 c0 e8 41
RIP  [<ffffffff8171a95e>] __ip6_datagram_connect+0x71e/0xa20
 RSP <ffff880129a17da8>
CR2: 00000000000000a0
====================

Signed-off-by: David S. Miller <davem@davemloft.net>