syzbot

==================================================================
BUG: KASAN: stack-out-of-bounds in get_frame_pointer arch/x86/include/asm/stacktrace.h:64 [inline]
BUG: KASAN: stack-out-of-bounds in __unwind_start+0x37c/0x3c0 arch/x86/kernel/unwind_frame.c:76
Read of size 8 at addr ffff8801cfdffc88 by task syz-executor056/5798

CPU: 0 PID: 5798 Comm: syz-executor056 Not tainted 4.9.118-g47b77b8 #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801c8e6f140 ffffffff81eb4b89 ffffea00073f7fc0 ffff8801cfdffc88
 0000000000000000 ffff8801cfdffc88 ffff8801c8e6f278 ffff8801c8e6f178
 ffffffff81567f29 ffff8801cfdffc88 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81eb4b89>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4b89>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81567f29>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81568333>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81568333>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff8153beb4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff810d323c>] get_frame_pointer arch/x86/include/asm/stacktrace.h:64 [inline]
 [<ffffffff810d323c>] __unwind_start+0x37c/0x3c0 arch/x86/kernel/unwind_frame.c:76
 [<ffffffff8107b9a9>] unwind_start arch/x86/include/asm/unwind.h:39 [inline]
 [<ffffffff8107b9a9>] __save_stack_trace+0x59/0xf0 arch/x86/kernel/stacktrace.c:41
 [<ffffffff8107baa8>] save_stack_trace_tsk+0x48/0x70 arch/x86/kernel/stacktrace.c:71
 [<ffffffff816d7dc8>] proc_pid_stack+0x148/0x220 fs/proc/base.c:469
 [<ffffffff816d94bd>] proc_single_show+0xfd/0x170 fs/proc/base.c:771
 [<ffffffff815ed7b6>] seq_read+0x4b6/0x12e0 fs/seq_file.c:240
 [<ffffffff8156f7b5>] do_loop_readv_writev.part.18+0xd5/0x280 fs/read_write.c:718
 [<ffffffff81573705>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff81573705>] do_readv_writev+0x565/0x7a0 fs/read_write.c:873
 [<ffffffff815739c4>] vfs_readv+0x84/0xc0 fs/read_write.c:897
 [<ffffffff81614b5b>] kernel_readv fs/splice.c:363 [inline]
 [<ffffffff81614b5b>] default_file_splice_read+0x44b/0x7e0 fs/splice.c:435
 [<ffffffff81613c5c>] do_splice_to+0x10c/0x170 fs/splice.c:899
 [<ffffffff81613eff>] splice_direct_to_actor+0x23f/0x7e0 fs/splice.c:971
 [<ffffffff81614643>] do_splice_direct+0x1a3/0x270 fs/splice.c:1080
 [<ffffffff815759d0>] do_sendfile+0x4f0/0xc60 fs/read_write.c:1393
 [<ffffffff81577a51>] SYSC_sendfile64 fs/read_write.c:1448 [inline]
 [<ffffffff81577a51>] SyS_sendfile64+0xd1/0x160 fs/read_write.c:1440
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fca93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea00073f7fc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cfdffb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cfdffc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801cfdffc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                      ^
 ffff8801cfdffd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cfdffd80: 00 00 f1 f1 f1 f1 00 f2 f2 f2 f2 f2 f2 f2 00 f2
==================================================================