==================================================================
BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0xcd/0xe0 arch/x86/kernel/unwind_frame.c:51
Read of size 8 at addr ffff88018a5c78d0 by task syz-executor6/21925

CPU: 0 PID: 21925 Comm: syz-executor6 Not tainted 4.9.105-gd7e64f8 #43
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff880177787178 ffffffff81eb41a9 ffffea00062971c0 ffff88018a5c78d0
 0000000000000000 ffff88018a5c78d0 ffff8801d926b140 ffff8801777871b0
 ffffffff81567e49 ffff88018a5c78d0 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81eb41a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb41a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81567e49>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81568253>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81568253>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff8153bea4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff810d2e5d>] unwind_next_frame+0xcd/0xe0 arch/x86/kernel/unwind_frame.c:51
 [<ffffffff8107b9dd>] __save_stack_trace+0x7d/0xf0 arch/x86/kernel/stacktrace.c:42
 [<ffffffff8107bab8>] save_stack_trace_tsk+0x48/0x70 arch/x86/kernel/stacktrace.c:71
 [<ffffffff816d7fe8>] proc_pid_stack+0x148/0x220 fs/proc/base.c:469
 [<ffffffff816d96dd>] proc_single_show+0xfd/0x170 fs/proc/base.c:771
 [<ffffffff815ed676>] seq_read+0x4b6/0x12e0 fs/seq_file.c:240
 [<ffffffff8156f6d5>] do_loop_readv_writev.part.18+0xd5/0x280 fs/read_write.c:718
 [<ffffffff81573625>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff81573625>] do_readv_writev+0x565/0x7a0 fs/read_write.c:873
 [<ffffffff815738e4>] vfs_readv+0x84/0xc0 fs/read_write.c:897
 [<ffffffff81614a1b>] kernel_readv fs/splice.c:363 [inline]
 [<ffffffff81614a1b>] default_file_splice_read+0x44b/0x7e0 fs/splice.c:435
 [<ffffffff81613b1c>] do_splice_to+0x10c/0x170 fs/splice.c:899
 [<ffffffff81613dbf>] splice_direct_to_actor+0x23f/0x7e0 fs/splice.c:971
 [<ffffffff81614503>] do_splice_direct+0x1a3/0x270 fs/splice.c:1080
 [<ffffffff815758f0>] do_sendfile+0x4f0/0xc60 fs/read_write.c:1393
 [<ffffffff81577ad1>] C_SYSC_sendfile fs/read_write.c:1469 [inline]
 [<ffffffff81577ad1>] compat_SyS_sendfile+0xd1/0x160 fs/read_write.c:1458
 [<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
 [<ffffffff839fb210>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

The buggy address belongs to the page:
page:ffffea00062971c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88018a5c7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88018a5c7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88018a5c7880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff88018a5c7900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88018a5c7980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================