syzbot

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BUG: KASAN: out-of-bounds in unwind_get_return_address+0x98/0xb0 arch/x86/kernel/unwind_frame.c:17
Read of size 8 at addr ffff8801d8ccf8e0 by task syz-executor806/3800

CPU: 1 PID: 3800 Comm: syz-executor806 Not tainted 4.9.96-g8c01d00 #11
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8d677c8 ffffffff81eb0b69 ffffea00076333c0 ffff8801d8ccf8e0
 0000000000000000 ffff8801d8ccf8e8 ffff8801d96d48c0 ffff8801d8d67800
 ffffffff8156540b ffff8801d8ccf8e0 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81eb0b69>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0b69>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8156540b>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81565815>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81565815>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff81539494>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff810d0c08>] unwind_get_return_address+0x98/0xb0 arch/x86/kernel/unwind_frame.c:17
 [<ffffffff8107addd>] __save_stack_trace+0x8d/0xf0 arch/x86/kernel/stacktrace.c:43
 [<ffffffff8107aea8>] save_stack_trace_tsk+0x48/0x70 arch/x86/kernel/stacktrace.c:71
 [<ffffffff816d5378>] proc_pid_stack+0x148/0x220 fs/proc/base.c:467
 [<ffffffff816d681d>] proc_single_show+0xfd/0x170 fs/proc/base.c:769
 [<ffffffff815eaa16>] seq_read+0x4b6/0x12e0 fs/seq_file.c:240
 [<ffffffff8156cc95>] do_loop_readv_writev.part.18+0xd5/0x280 fs/read_write.c:718
 [<ffffffff81570be5>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff81570be5>] do_readv_writev+0x565/0x7a0 fs/read_write.c:873
 [<ffffffff81570ea4>] vfs_readv+0x84/0xc0 fs/read_write.c:897
 [<ffffffff81570fc6>] do_readv+0xe6/0x260 fs/read_write.c:923
 [<ffffffff81574827>] SYSC_readv fs/read_write.c:1010 [inline]
 [<ffffffff81574827>] SyS_readv+0x27/0x30 fs/read_write.c:1007
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f3313>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea00076333c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d8ccf780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d8ccf800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801d8ccf880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                          ^
 ffff8801d8ccf900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d8ccf980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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