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BUG: KASAN: stack-out-of-bounds in deref_stack_reg+0x1b8/0x1d0
Read of size 8 at addr ffff8801c63ff210 by task syz-executor4/7819

CPU: 0 PID: 7819 Comm: syz-executor4 Not tainted 4.14.0-rc5-next-20171017+ #34
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 dump_stack+0x173/0x237
 print_address_description+0x6e/0x250
 kasan_report+0x251/0x340
 deref_stack_reg+0x1b8/0x1d0
 unwind_next_frame+0xebc/0x1df0
 __save_stack_trace+0x6e/0xd0
 save_stack+0x32/0xb0
 kasan_slab_free+0x71/0xc0
 kfree+0xc8/0x250
 security_cred_free+0x42/0x80
 put_cred_rcu+0xee/0x3c0
 rcu_process_callbacks+0xcd4/0x1600
 __do_softirq+0x2ba/0xafb
 irq_exit+0x1c7/0x200
 smp_apic_timer_interrupt+0x154/0x6b0
 apic_timer_interrupt+0x96/0xa0
 </IRQ>
RIP: 0010:lock_is_held_type+0x84/0x200
RSP: 0018:ffff8801c63ff098 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff11
RAX: dffffc0000000000 RBX: ffff8801ca5aa2c0 RCX: 0000000000000000
RDX: 1ffffffff0ad8f50 RSI: 00000000ffffffff RDI: ffffffff856c7a80
RBP: ffff8801dac78680 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85737c60
R13: ffffffff81941b12 R14: ffff8801c0515cc0 R15: ffff8801d0702e58
 unlink_anon_vmas+0x1e2/0x900

The buggy address belongs to the page:
page:ffffea000718ffc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x200000000000000()
raw: 0200000000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c63ff100: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 f8 f2 f2 f2
 ffff8801c63ff180: f2 f2 f2 f2 f8 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2
>ffff8801c63ff200: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
                         ^
 ffff8801c63ff280: 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 00
 ffff8801c63ff300: 00 00 00 00 00 00 00 00 00 00 00 f2 f2 f2 f3 f3
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