==================================================================
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 ffff8801cd707890 by task syz-executor7/20381

CPU: 1 PID: 20381 Comm: syz-executor7 Not tainted 4.9.93-geba1ffe #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801963277b8 ffffffff81d9c2b9 ffffea000735c1c0 ffff8801cd707890
 0000000000000000 ffff8801cd707898 ffff8801a0be0280 ffff8801963277f0
 ffffffff8156536b ffff8801cd707890 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81d9c2b9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9c2b9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8156536b>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff815655df>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff815655df>] kasan_report.cold.6+0xac/0x2f5 mm/kasan/report.c:412
 [<ffffffff815393f4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff810d0c78>] 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
 [<ffffffff816cd5a8>] proc_pid_stack+0x148/0x220 fs/proc/base.c:467
 [<ffffffff816cea4d>] proc_single_show+0xfd/0x170 fs/proc/base.c:769
 [<ffffffff815ea8a6>] seq_read+0x4b6/0x12e0 fs/seq_file.c:240
 [<ffffffff8156cc05>] do_loop_readv_writev.part.18+0xd5/0x280 fs/read_write.c:718
 [<ffffffff81571db7>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff81571db7>] compat_do_readv_writev+0x567/0x7a0 fs/read_write.c:1091
 [<ffffffff815720d2>] compat_readv+0xe2/0x150 fs/read_write.c:1120
 [<ffffffff81572462>] do_compat_preadv64+0x152/0x180 fs/read_write.c:1169
 [<ffffffff815749fb>] C_SYSC_preadv fs/read_write.c:1189 [inline]
 [<ffffffff815749fb>] compat_SyS_preadv+0x3b/0x50 fs/read_write.c:1183
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff838d7050>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

The buggy address belongs to the page:
page:ffffea000735c1c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cd707780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cd707800: 00 f1 f1 f1 f1 00 00 00 00 f3 f3 f3 f3 00 00 00
>ffff8801cd707880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                            ^
 ffff8801cd707900: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00
 ffff8801cd707980: 00 f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================