kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 4818 Comm: syz-executor3 Not tainted 4.4.161+ #110
task: ffff8800b3de2f80 task.stack: ffff8801c0828000
RIP: 0010:[<ffffffff81d29898>]  [<ffffffff81d29898>] is_loop_device drivers/block/loop.c:656 [inline]
RIP: 0010:[<ffffffff81d29898>]  [<ffffffff81d29898>] loop_validate_file+0x208/0x400 drivers/block/loop.c:667
RSP: 0018:ffff8801c082fb70  EFLAGS: 00010206
RAX: 0000000000000036 RBX: dffffc0000000000 RCX: ffffc9000334a000
RDX: 0000000000000088 RSI: ffffffff81d29868 RDI: 00000000000001b0
RBP: ffff8801c082fb88 R08: ffff8800b3de3848 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: ffff8801da2678c0 R14: ffff8801da2678c0 R15: ffff8800ba814ed8
FS:  00007facf7b8f700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000206b61ff CR3: 00000000b381b000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8800ba814d80 0000000000004c00 ffff8801cf664400 ffff8801c082fc18
 ffffffff81d33077 1ffff10038105f78 0000002e00000000 0000000000000000
 00000001000000cf 0000000000000000 0000000041b58ab3 ffff8800ba814ed0
Call Trace:
 [<ffffffff81d33077>] loop_set_fd drivers/block/loop.c:920 [inline]
 [<ffffffff81d33077>] lo_ioctl+0x6a7/0x16b0 drivers/block/loop.c:1367
 [<ffffffff81a66ae6>] __blkdev_driver_ioctl block/ioctl.c:288 [inline]
 [<ffffffff81a66ae6>] blkdev_ioctl+0x7a6/0x19a0 block/ioctl.c:584
 [<ffffffff8154962e>] block_ioctl+0xde/0x120 fs/block_dev.c:1625
 [<ffffffff814cbb6f>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff814cbb6f>] file_ioctl fs/ioctl.c:470 [inline]
 [<ffffffff814cbb6f>] do_vfs_ioctl+0x63f/0xf40 fs/ioctl.c:605
 [<ffffffff814cc4ff>] SYSC_ioctl fs/ioctl.c:622 [inline]
 [<ffffffff814cc4ff>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
 [<ffffffff82705b21>] entry_SYSCALL_64_fastpath+0x1e/0x9a
Code: 00 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 f7 01 00 00 4d 8b a4 24 f0 00 00 00 49 8d bc 24 b0 01 00 00 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 cc 01 00 00 4d 8b a4 24 b0 01 00 00 4c 89 e0 
RIP  [<ffffffff81d29898>] is_loop_device drivers/block/loop.c:656 [inline]
RIP  [<ffffffff81d29898>] loop_validate_file+0x208/0x400 drivers/block/loop.c:667
 RSP <ffff8801c082fb70>
---[ end trace 6b127ce9861adbad ]---