FAT-fs (loop4): error, invalid access to FAT (entry 0x000006c0)
FAT-fs (loop4): Filesystem has been set read-only
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BUG: KASAN: stack-out-of-bounds in __read_once_size include/linux/compiler.h:188 [inline]
BUG: KASAN: stack-out-of-bounds in update_stack_state+0x5d9/0x670 arch/x86/kernel/unwind_frame.c:270
Read of size 8 at addr ffff8801871af1d8 by task syz-executor4/11662

CPU: 0 PID: 11662 Comm: syz-executor4 Not tainted 4.17.0-rc3+ #31
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+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __read_once_size include/linux/compiler.h:188 [inline]
 update_stack_state+0x5d9/0x670 arch/x86/kernel/unwind_frame.c:270
 __unwind_start+0xf9/0x330 arch/x86/kernel/unwind_frame.c:404
 unwind_start arch/x86/include/asm/unwind.h:54 [inline]
 perf_callchain_kernel+0x2ab/0x630 arch/x86/events/core.c:2350
 get_perf_callchain+0x515/0xb20 kernel/events/callchain.c:202
 perf_callchain kernel/events/core.c:6357 [inline]
 perf_prepare_sample+0x123d/0x1900 kernel/events/core.c:6383
 __perf_event_output kernel/events/core.c:6497 [inline]
 perf_event_output_forward+0x10a/0x2b0 kernel/events/core.c:6515
 __perf_event_overflow+0x231/0x4b0 kernel/events/core.c:7755
 perf_swevent_overflow+0xad/0x150 kernel/events/core.c:7831
 perf_swevent_event+0x1f0/0x2e0 kernel/events/core.c:7864
 do_perf_sw_event kernel/events/core.c:7972 [inline]
 ___perf_sw_event+0x486/0x780 kernel/events/core.c:8003
 perf_sw_event_sched include/linux/perf_event.h:1062 [inline]
 perf_event_task_sched_out include/linux/perf_event.h:1100 [inline]
 prepare_task_switch kernel/sched/core.c:2636 [inline]
 context_switch kernel/sched/core.c:2813 [inline]
 __schedule+0xf3f/0x1e30 kernel/sched/core.c:3490
 preempt_schedule_common+0x22/0x60 kernel/sched/core.c:3629
 _cond_resched+0x1d/0x30 kernel/sched/core.c:4978
 down_read+0x91/0x1b0 kernel/locking/rwsem.c:23
 iterate_supers+0xe2/0x290 fs/super.c:618
 ksys_sync+0xf7/0x1d0 fs/sync.c:114
 __ia32_sys_sync+0xe/0x20 fs/sync.c:124
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455979
RSP: 002b:00007f7a31ce3c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f7a31ce46d4 RCX: 0000000000455979
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000006a4 R14: 00000000006fe000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea00061c6bc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea00061c0101 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801871af080: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00
 ffff8801871af100: 00 00 00 00 00 00 00 00 f2 f3 f3 f3 f3 00 00 00
>ffff8801871af180: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2
                                                    ^
 ffff8801871af200: f2 f2 f2 f2 f2 f2 f8 f2 f2 f2 f2 f2 f2 f2 00 00
 ffff8801871af280: 00 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00
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