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BUG: KASAN: stack-out-of-bounds in update_stack_state+0x5db/0x690 arch/x86/kernel/unwind_frame.c:266
Read of size 8 at addr ffff880194a2fa80 by task syz-executor3/7575

CPU: 0 PID: 7575 Comm: syz-executor3 Not tainted 4.19.0-rc3+ #139
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 update_stack_state+0x5db/0x690 arch/x86/kernel/unwind_frame.c:266
 unwind_next_frame.part.7+0x1ae/0x9e0 arch/x86/kernel/unwind_frame.c:329
 unwind_next_frame+0x3e/0x50 arch/x86/kernel/unwind_frame.c:287
 __save_stack_trace+0x7d/0xf0 arch/x86/kernel/stacktrace.c:44
 save_stack_trace_tsk+0x9c/0xd0 arch/x86/kernel/stacktrace.c:76
 proc_pid_stack+0x217/0x3b0 fs/proc/base.c:424
 proc_single_show+0x101/0x190 fs/proc/base.c:723
 seq_read+0x4af/0x1150 fs/seq_file.c:229
 do_loop_readv_writev fs/read_write.c:700 [inline]
 do_iter_read+0x4a3/0x650 fs/read_write.c:924
 compat_readv+0x1b4/0x260 fs/read_write.c:1167
 do_compat_preadv64+0x190/0x1c0 fs/read_write.c:1216
 __do_compat_sys_preadv fs/read_write.c:1236 [inline]
 __se_compat_sys_preadv fs/read_write.c:1230 [inline]
 __ia32_compat_sys_preadv+0xc7/0x140 fs/read_write.c:1230
 do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
 do_fast_syscall_32+0x34d/0xfb2 arch/x86/entry/common.c:397
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fd8ca9
Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 0c 24 c3 8b 1c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5fd40cc EFLAGS: 00000296 ORIG_RAX: 000000000000014d
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000480
RDX: 0000000000000198 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006528bc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 ffffea0006528bc8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880194a2f980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
 ffff880194a2fa00: f1 f1 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f2 f2
>ffff880194a2fa80: f2 f2 00 f2 f2 f2 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff880194a2fb00: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f2 f2 f2
 ffff880194a2fb80: f2 f2 f2 f2 00 00 f2 f2 f2 f2 f2 f2 04 f2 f2 f2
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IPVS: ftp: loaded support on port[0] = 21