general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f] CPU: 0 PID: 9476 Comm: syz-executor.4 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:workqueue_sysfs_unregister kernel/workqueue.c:5691 [inline] RIP: 0010:destroy_workqueue+0x2e/0x6b0 kernel/workqueue.c:4351 Code: 49 89 fe 41 55 41 54 55 53 48 83 ec 08 e8 8a 6a 26 00 49 8d be 08 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 05 00 00 49 8b 9e 08 01 00 00 48 85 db 74 19 RSP: 0018:ffffc900022c7cc8 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000 RDX: 0000000000000021 RSI: ffffffff814c2af6 RDI: 0000000000000108 RBP: ffff8882189b58f0 R08: ffff888055b28340 R09: fffffbfff185270a R10: fffffbfff1852709 R11: ffffffff8c29384f R12: ffff8882189b5800 R13: ffff8882189b5804 R14: 0000000000000000 R15: 0000000000004c01 FS: 0000000001a7e940(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa10ddf8df8 CR3: 0000000055af5000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: loop_unprepare_queue drivers/block/loop.c:891 [inline] __loop_clr_fd+0x185/0x1280 drivers/block/loop.c:1210 loop_clr_fd drivers/block/loop.c:1335 [inline] lo_ioctl+0x2b4/0x1460 drivers/block/loop.c:1704 __blkdev_driver_ioctl block/ioctl.c:321 [inline] blkdev_ioctl+0x25b/0x660 block/ioctl.c:717 block_ioctl+0xe9/0x130 fs/block_dev.c:1983 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770 do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c6b7 Code: 48 83 c4 08 48 89 d8 5b 5d c3 66 0f 1f 84 00 00 00 00 00 48 89 e8 48 f7 d8 48 39 c3 0f 92 c0 eb 92 66 90 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 0d b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffe38607708 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045c6b7 RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000003 RBP: 000000000000001d R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe38607740 R14: 00000000000439c2 R15: 00007ffe38607750 Modules linked in: ---[ end trace 46e73030900f9791 ]--- RIP: 0010:workqueue_sysfs_unregister kernel/workqueue.c:5691 [inline] RIP: 0010:destroy_workqueue+0x2e/0x6b0 kernel/workqueue.c:4351 Code: 49 89 fe 41 55 41 54 55 53 48 83 ec 08 e8 8a 6a 26 00 49 8d be 08 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 05 00 00 49 8b 9e 08 01 00 00 48 85 db 74 19 RSP: 0018:ffffc900022c7cc8 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000 RDX: 0000000000000021 RSI: ffffffff814c2af6 RDI: 0000000000000108 RBP: ffff8882189b58f0 R08: ffff888055b28340 R09: fffffbfff185270a R10: fffffbfff1852709 R11: ffffffff8c29384f R12: ffff8882189b5800 R13: ffff8882189b5804 R14: 0000000000000000 R15: 0000000000004c01 FS: 0000000001a7e940(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa10ddf8df8 CR3: 0000000055af5000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400