KASAN: stack-out-of-bounds Read in futex

Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported
BUG: unable to handle kernel paging request in ttwu_do_activate kernel				1	2361d	2361d

device lo entered promiscuous mode
==================================================================
BUG: KASAN: stack-out-of-bounds in futex_wake+0x6b9/0x760 kernel/futex.c:1538
Read of size 8 at addr ffff880195ac77b0 by task syz-executor5/9986

CPU: 0 PID: 9986 Comm: syz-executor5 Not tainted 4.18.0-rc3+ #58
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 futex_wake+0x6b9/0x760 kernel/futex.c:1538
 do_futex+0x300/0x27d0 kernel/futex.c:3531
 __do_sys_futex kernel/futex.c:3587 [inline]
 __se_sys_futex kernel/futex.c:3555 [inline]
 __x64_sys_futex+0x472/0x6a0 kernel/futex.c:3555
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455ab9
Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007ffc317a94e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 000000000072bf48 RCX: 0000000000455ab9
RDX: 00000000000000a8 RSI: 0000000000000001 RDI: 000000000072bf68
RBP: 00000000000004f8 R08: 00007ffc317a9630 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 000000000000000f
R13: 00007ffc317a9630 R14: 000000000072bf6c R15: 0000000000000001

The buggy address belongs to the page:
page:ffffea000656b1c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 ffffffff06560101 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880195ac7680: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff880195ac7700: 00 00 00 00 00 00 f1 f1 f1 f1 00 f2 f2 f2 f2 f2
>ffff880195ac7780: f2 f2 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f2 f2
                                     ^
 ffff880195ac7800: f2 f2 f8 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 00 00
 ffff880195ac7880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Time	Kernel	Commit	Syzkaller	Config	Log	Report	Manager
2018/07/19 17:14	bpf-next	8ae71e76cf1f	49f35839	.config	console log	report	ci-upstream-bpf-next-kasan-gce
2018/07/17 14:10	bpf-next	301f935be9e0	13761366	.config	console log	report	ci-upstream-bpf-next-kasan-gce
2018/07/08 13:42	bpf-next	d90c936fb318	c9a7a4dc	.config	console log	report	ci-upstream-bpf-next-kasan-gce
2018/07/05 10:07	bpf-next	6fcf9b1d4d6c	f525fd72	.config	console log	report	ci-upstream-bpf-next-kasan-gce
2018/07/05 03:55	bpf-next	2bdea157b999	e1b966c6	.config	console log	report	ci-upstream-bpf-next-kasan-gce