FAT-fs (loop4): bogus number of reserved sectors
FAT-fs (loop4): Can't find a valid FAT filesystem
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
CPU: 0 PID: 8200 Comm: syz-executor7 Not tainted 4.18.0-rc5-next-20180718+ #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:loop_validate_file+0x247/0x470 drivers/block/loop.c:664
Code: 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 2e 02 00 00 4d 8b a4 24 f0 00 00 00 49 8d bc 24 b8 01 00 00 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 03 02 00 00 4d 8b a4 24 b8 01 00 00 4c 89 e0 48 
RSP: 0018:ffff88019bfb78f8 EFLAGS: 00010202
RAX: 0000000000000037 RBX: dffffc0000000000 RCX: ffffc90002620000
RDX: 000000000000003d RSI: ffffffff84c8a737 RDI: 00000000000001b8
RBP: ffff88019bfb7918 R08: ffff8801914043c0 R09: ffffed00337f6efb
R10: ffffed00337f6efb R11: ffff88019bfb77df R12: 0000000000000000
R13: ffff8801b308a640 R14: 0000000000000002 R15: ffff8801b308a640
FS:  00007fb83733c700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2c422000 CR3: 00000001adc8c000 CR4: 00000000001406f0
DR0: 000000000000b8c4 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 loop_set_fd drivers/block/loop.c:926 [inline]
 lo_ioctl+0x55c/0x1d70 drivers/block/loop.c:1409
 __blkdev_driver_ioctl block/ioctl.c:303 [inline]
 blkdev_ioctl+0x9cd/0x2030 block/ioctl.c:601
 block_ioctl+0xee/0x130 fs/block_dev.c:1880
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:684
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455ab9
Code: 1d ba 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 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007fb83733bc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb83733c6d4 RCX: 0000000000455ab9
RDX: 0000000000000014 RSI: 0000000000004c00 RDI: 0000000000000015
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004be0ab R14: 00000000004ccbb0 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 191d3c03329f8078 ]---
RIP: 0010:loop_validate_file+0x247/0x470 drivers/block/loop.c:664
Code: 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 2e 02 00 00 4d 8b a4 24 f0 00 00 00 49 8d bc 24 b8 01 00 00 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 03 02 00 00 4d 8b a4 24 b8 01 00 00 4c 89 e0 48 
RSP: 0018:ffff88019bfb78f8 EFLAGS: 00010202
RAX: 0000000000000037 RBX: dffffc0000000000 RCX: ffffc90002620000
RDX: 000000000000003d RSI: ffffffff84c8a737 RDI: 00000000000001b8
RBP: ffff88019bfb7918 R08: ffff8801914043c0 R09: ffffed00337f6efb
R10: ffffed00337f6efb R11: ffff88019bfb77df R12: 0000000000000000
R13: ffff8801b308a640 R14: 0000000000000002 R15: ffff8801b308a640
FS:  00007fb83733c700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2c422000 CR3: 00000001adc8c000 CR4: 00000000001406f0
DR0: 000000000000b8c4 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400