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BUG: KASAN: stack-out-of-bounds in deref_stack_reg+0x1b8/0x1d0
Read of size 8 at addr ffff8801cbee7198 by task syz-executor5/3204

CPU: 1 PID: 3204 Comm: syz-executor5 Not tainted 4.14.0-rc5-mm1+ #17
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:ffff8801cbee7088 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff11
RAX: dffffc0000000000 RBX: ffff8801d2f82080 RCX: 0000000000000000
RDX: 1ffffffff0ad8f48 RSI: 00000000ffffffff RDI: ffffffff856c7a40
RBP: 0000000000000040 R08: 0000000000000001 R09: 00000000b5842c68
R10: 00000000c0c7652a R11: 0000000000000000 R12: ffffffff85737ce0
R13: 0000000000000060 R14: 00000000014000c0 R15: ffff8801d037c060
 anon_vma_fork+0x2a9/0x770
 copy_mm+0x824/0x11f2
 copy_process.part.39+0x2091/0x4b20

The buggy address belongs to the page:
page:ffffea00072fb9c0 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:
 ffff8801cbee7080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cbee7100: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
>ffff8801cbee7180: f8 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f3 f3 f3 f3
                            ^
 ffff8801cbee7200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cbee7280: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f2 f2
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