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BUG: KASAN: out-of-bounds in unwind_get_return_address+0x8f/0xa0 arch/x86/kernel/unwind_frame.c:17
Read of size 8 at addr ffff8801c8ccf848 by task syz-executor4/7548

CPU: 1 PID: 7548 Comm: syz-executor4 Not tainted 4.9.128+ #93
 ffff8801c7e4fb58 ffffffff81af2469 ffffea00072333c0 ffff8801c8ccf848
 0000000000000000 ffff8801c8ccf850 ffff8801c9146c80 ffff8801c7e4fb90
 ffffffff814e13cb ffff8801c8ccf848 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81af2469>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81af2469>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff814e13cb>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff814e17d5>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff814e17d5>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff814d3c14>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff810aa8df>] unwind_get_return_address+0x8f/0xa0 arch/x86/kernel/unwind_frame.c:17
 [<ffffffff81075fbd>] __save_stack_trace+0x8d/0xf0 arch/x86/kernel/stacktrace.c:43
 [<ffffffff81076088>] save_stack_trace_tsk+0x48/0x70 arch/x86/kernel/stacktrace.c:71
 [<ffffffff8163e2b8>] proc_pid_stack+0x148/0x220 fs/proc/base.c:469
 [<ffffffff8163683d>] proc_single_show+0xfd/0x170 fs/proc/base.c:771
 [<ffffffff8155e0a3>] traverse+0x363/0x920 fs/seq_file.c:124
 [<ffffffff8155e7a0>] seq_lseek+0x140/0x3c0 fs/seq_file.c:337
 [<ffffffff814eaac7>] vfs_llseek fs/read_write.c:298 [inline]
 [<ffffffff814eaac7>] SYSC_lseek fs/read_write.c:311 [inline]
 [<ffffffff814eaac7>] SyS_lseek+0x117/0x180 fs/read_write.c:302
 [<ffffffff8100554f>] do_syscall_64+0x19f/0x480 arch/x86/entry/common.c:282
 [<ffffffff8278df13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea00072333c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c8ccf700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c8ccf780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801c8ccf800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff8801c8ccf880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c8ccf900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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