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BUG: KASAN: out-of-bounds in deref_stack_regs arch/x86/kernel/unwind_orc.c:304 [inline]
BUG: KASAN: out-of-bounds in unwind_next_frame+0x1424/0x1700 arch/x86/kernel/unwind_orc.c:434
Read of size 8 at addr ffff8881e1157e78 by task syz-executor.2/7052

CPU: 1 PID: 7052 Comm: syz-executor.2 Not tainted 4.14.181-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2b9 mm/kasan/report.c:393
 deref_stack_regs arch/x86/kernel/unwind_orc.c:304 [inline]
 unwind_next_frame+0x1424/0x1700 arch/x86/kernel/unwind_orc.c:434
 __save_stack_trace+0x6b/0xd0 arch/x86/kernel/stacktrace.c:44
 save_stack_trace_tsk arch/x86/kernel/stacktrace.c:73 [inline]
 save_stack_trace_tsk+0x34/0x40 arch/x86/kernel/stacktrace.c:68
 proc_pid_stack+0x164/0x240 fs/proc/base.c:459
 proc_single_show+0xe7/0x150 fs/proc/base.c:761
 seq_read+0x4d2/0x1130 fs/seq_file.c:237
 do_loop_readv_writev fs/read_write.c:695 [inline]
 do_loop_readv_writev fs/read_write.c:682 [inline]
 do_iter_read+0x3e3/0x5a0 fs/read_write.c:919
 vfs_readv+0xd3/0x130 fs/read_write.c:981
 do_preadv+0x161/0x200 fs/read_write.c:1065
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ca29
RSP: 002b:00007f74f9ae9c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000004fa6c0 RCX: 000000000045ca29
RDX: 000000000000037d RSI: 0000000020000500 RDI: 0000000000000009
RBP: 000000000078c180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000862 R14: 00000000004cb43c R15: 00007f74f9aea6d4

The buggy address belongs to the page:
page:ffffea00078455c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x57ffe0000000000()
raw: 057ffe0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881e1157d80: 00 00 00 00 00 00 00 f1 f1 f1 f1 f1 f1 00 00 00
 ffff8881e1157e00: 00 00 00 00 00 00 f3 f3 f3 f3 f3 00 00 00 00 00
>ffff8881e1157e80: 00 00 f1 f1 f1 f1 00 00 f3 f3 00 00 00 00 00 00
                   ^
 ffff8881e1157f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881e1157f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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