WARNING in loop_add

[Wei Chen]

Dear Linux Developer,

Recently when using our tool to fuzz kernel, the following crash was triggered:

HEAD commit: 64570fbc14f8 Linux 5.15-rc5
git tree: upstream
compiler: clang 12.0.0
console output:
https://drive.google.com/file/d/1JxspkioQiZrQQ9BwsRjm5KJVY6z2KCTW/view?usp=sharing
Syzlang reproducer:
https://drive.google.com/file/d/1b7QJc_OVw-U7ugxWyvisfMbyQe-aBjWZ/view?usp=sharing
C reproducer: https://drive.google.com/file/d/1ymwqhBp9VYd7jRdpcfwiqUSUV0BnzCC0/view?usp=sharing
kernel config: https://drive.google.com/file/d/1lNwvovjLNrcuyFGrg05IoSmgO5jaKBBJ/view?usp=sharing

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: Wei Chen <harperchen1110@xxxxxxxxx>

WARNING: CPU: 0 PID: 8479 at block/genhd.c:537 device_add_disk+0x8aa/0xf20
Modules linked in:
CPU: 0 PID: 8479 Comm: syz-executor Not tainted 5.15.0-rc5+ #14
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:device_add_disk+0x8aa/0xf20
Code: 00 48 8b 44 24 10 89 18 e8 93 8e 6a fd 4c 89 e7 e8 7b 66 fb ff
4c 89 e7 e8 73 ca 03 00 45 31 f6 e9 b1 fe ff ff e8 76 8e 6a fd <0f> 0b
e9 96 fe ff ff e8 6a 8e 6a fd 0f 0b 41 be ea ff ff ff e9 93
RSP: 0018:ffffc9000b297d28 EFLAGS: 00010283
RAX: ffffffff841b4a0a RBX: 0000000000000007 RCX: 0000000000040000
RDX: ffffc90002211000 RSI: 000000000002f3b2 RDI: 000000000002f3b3
RBP: ffff88803017bb00 R08: ffffffff841b4899 R09: ffffed100c7864a2
R10: ffffed100c7864a2 R11: 0000000000000000 R12: ffff88802f915000
R13: 00000000ffffffea R14: 1ffff11005f22a00 R15: 1ffff11005f22a01
FS:  00007ff387033700(0000) GS:ffff888063c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f65c6510000 CR3: 0000000030409000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 loop_add+0x62d/0x8c0
 loop_control_ioctl+0x11d/0x770
 __se_sys_ioctl+0x10a/0x190
 do_syscall_64+0x3d/0xb0
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7ff389acac4d
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff387032c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff389bf10a0 RCX: 00007ff389acac4d
RDX: 0000000000000000 RSI: 0000000000004c80 RDI: 0000000000000004
RBP: 00007ff387032c90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000026
R13: 00007fff0e90e49f R14: 00007fff0e90e640 R15: 00007ff387032dc0

Best,
Wei