kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 2 PID: 4830 Comm: syz-executor3 Not tainted 4.14.0-rc5-next-20171018+ #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff880039b463c0 task.stack: ffff88003b7f0000
RIP: 0010:bdev_get_queue include/linux/blkdev.h:981 [inline]
RIP: 0010:bdev_logical_block_size include/linux/blkdev.h:1417 [inline]
RIP: 0010:bd_set_size+0x5f/0x330 fs/block_dev.c:1383
RSP: 0018:ffff88003b7f7108 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81bb650c
RDX: 00000000000000aa RSI: 0000000000000000 RDI: 0000000000000550
RBP: ffff88003b7f7138 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88003d3b6200
R13: 0000000000000000 R14: ffff880069f26940 R15: ffff880069f26c68
FS:  00007f7cd257b700(0000) GS:ffff88006de00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020941000 CR3: 000000003b72a000 CR4: 00000000000006e0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 loop_clr_fd+0x4fc/0xb50 drivers/block/loop.c:1053
 lo_release+0xee/0x180 drivers/block/loop.c:1598
 __blkdev_put+0x602/0x7c0 fs/block_dev.c:1770
 blkdev_put+0x85/0x4f0 fs/block_dev.c:1835
 blkdev_close+0x8b/0xb0 fs/block_dev.c:1842
 __fput+0x327/0x7e0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:112
 exit_task_work include/linux/task_work.h:21 [inline]
 do_exit+0x9b5/0x1ad0 kernel/exit.c:869
 do_group_exit+0x149/0x400 kernel/exit.c:972
 get_signal+0x73f/0x16d0 kernel/signal.c:2333
 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:808
 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath+0x42f/0x510 arch/x86/entry/common.c:266
 entry_SYSCALL_64_fastpath+0xbc/0xbe
RIP: 0033:0x447c89
RSP: 002b:00007f7cd257abd8 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: 0000000000000021 RBX: 00007f7cd257b6cc RCX: 0000000000447c89
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 000000002001d000
RBP: 00000000007480d8 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000005b80 R14: 00000000006e9c20 R15: 00007f7cd257b700
Code: 03 80 3c 02 00 0f 85 c6 02 00 00 49 8b 9c 24 e0 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d bb 50 05 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 76 02 00 00 4d 8d 74 24 08 48 b8 00 00 00 00 
RIP: bdev_get_queue include/linux/blkdev.h:981 [inline] RSP: ffff88003b7f7108
RIP: bdev_logical_block_size include/linux/blkdev.h:1417 [inline] RSP: ffff88003b7f7108
RIP: bd_set_size+0x5f/0x330 fs/block_dev.c:1383 RSP: ffff88003b7f7108
---[ end trace 113e881af5380414 ]---