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BUG: KASAN: null-ptr-deref in set_bit include/asm-generic/bitops-instrumented.h:28 [inline]
BUG: KASAN: null-ptr-deref in io_wq_cancel_all+0x28/0x2a0 fs/io-wq.c:624
Write of size 8 at addr 0000000000000004 by task syz-executor.1/25327

CPU: 0 PID: 25327 Comm: syz-executor.1 Not tainted 5.4.0-rc5-next-20191030 #0
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+0x172/0x1f0 lib/dump_stack.c:113
 __kasan_report.cold+0x5/0x41 mm/kasan/report.c:510
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192
 __kasan_check_write+0x14/0x20 mm/kasan/common.c:98
 set_bit include/asm-generic/bitops-instrumented.h:28 [inline]
 io_wq_cancel_all+0x28/0x2a0 fs/io-wq.c:624
 io_uring_flush+0x35a/0x4e0 fs/io_uring.c:3982
 filp_close+0xbd/0x170 fs/open.c:1174
 close_files fs/file.c:388 [inline]
 put_files_struct fs/file.c:416 [inline]
 put_files_struct+0x1d7/0x2f0 fs/file.c:413
 exit_files+0x83/0xb0 fs/file.c:445
 do_exit+0x8d2/0x2e60 kernel/exit.c:812
 do_group_exit+0x135/0x360 kernel/exit.c:921
 __do_sys_exit_group kernel/exit.c:932 [inline]
 __se_sys_exit_group kernel/exit.c:930 [inline]
 __x64_sys_exit_group+0x44/0x50 kernel/exit.c:930
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459f49
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffa248ba08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000001e RCX: 0000000000459f49
RDX: 0000000000413ae1 RSI: fffffffffffffff7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffff R09: 00007fffa248ba60
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffa248ba60 R14: 0000000000000000 R15: 00007fffa248ba70
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