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BUG: KASAN: out-of-bounds in unwind_next_frame.part.0+0x76d/0x8b0 arch/x86/kernel/unwind_frame.c:327
Read of size 8 at addr ffff88806d1d7e68 by task syz-executor.4/879

CPU: 0 PID: 879 Comm: syz-executor.4 Not tainted 4.14.146 #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+0x138/0x197 lib/dump_stack.c:53
 print_address_description.cold+0x7c/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+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 unwind_next_frame.part.0+0x76d/0x8b0 arch/x86/kernel/unwind_frame.c:327
 unwind_next_frame+0x3b/0x50 arch/x86/kernel/unwind_frame.c:287
 __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+0x3e/0x50 arch/x86/kernel/stacktrace.c:68
 proc_pid_stack+0x174/0x250 fs/proc/base.c:459
 proc_single_show+0xf0/0x160 fs/proc/base.c:761
 seq_read+0x51a/0x1280 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+0x3e2/0x5b0 fs/read_write.c:919
 vfs_readv+0xd3/0x130 fs/read_write.c:981
 do_preadv+0x15d/0x200 fs/read_write.c:1065
 SYSC_preadv fs/read_write.c:1115 [inline]
 SyS_preadv+0x31/0x40 fs/read_write.c:1110
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459a29
RSP: 002b:00007f2edbca6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459a29
RDX: 10000000000002a1 RSI: 0000000020000480 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2edbca76d4
R13: 00000000004c6d3d R14: 00000000004dc0b8 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea0001b475c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88806d1d7d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806d1d7d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806d1d7e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                             ^
 ffff88806d1d7e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806d1d7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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