WARNING in md_ioctl

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
c61a56ababa404961fa769a2b24229f18e461961 (Sun Apr 29 17:06:05 2018 +0000)
Merge branch 'x86-urgent-for-linus' of  
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=1e46a0864c1a6e9bd3d8

C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5771999158730752
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=6399853584187392
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6389218171420672
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=4617060493481910265
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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Reported-by: syzbot+1e46a0864c1a6e9bd3d8@xxxxxxxxxxxxxxxxxxxxxxxxx
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
md: md0 stopped.
md: md0 stopped.
WARNING: CPU: 1 PID: 4511 at drivers/md/md.c:7188 md_ioctl+0x3427/0x6360  
drivers/md/md.c:7188
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4511 Comm: syz-executor107 Not tainted 4.17.0-rc2+ #24
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+0x1b9/0x294 lib/dump_stack.c:113
 panic+0x22f/0x4de kernel/panic.c:184
 __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:md_ioctl+0x3427/0x6360 drivers/md/md.c:7188
RSP: 0018:ffff8801ad9b7400 EFLAGS: 00010293
RAX: ffff8801acf7a540 RBX: 0000000000000932 RCX: ffffffff8565f354
RDX: 0000000000000000 RSI: ffffffff85661c37 RDI: 0000000000000007
RBP: ffff8801ad9b79c0 R08: ffff8801acf7a540 R09: ffffed0039894699
R10: ffff8801ad9b73f0 R11: ffff8801cc4a34cf R12: 0000000000000932
R13: ffff8801cc4a3328 R14: ffff8801ad9b7998 R15: 0000000000000001
 __blkdev_driver_ioctl block/ioctl.c:303 [inline]
 blkdev_ioctl+0x9b6/0x2020 block/ioctl.c:601
 block_ioctl+0xee/0x130 fs/block_dev.c:1877
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1cf/0x16a0 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+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445a59
RSP: 002b:00007f00dd147da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445a59
RDX: 0000000020000080 RSI: 0000000000000932 RDI: 0000000000000003
RBP: 00000000006dac3c R08: 00007f00dd148700 R09: 0000000000000000
R10: 00007f00dd148700 R11: 0000000000000246 R12: 00000000006dac38
R13: 30646d2f7665642f R14: 00007f00dd1489c0 R15: 0000000000000003
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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