[syzbot] [mtd?] divide error in block2mtd_setup2

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    f5bbbfec59b4 Merge tag 'probes-fixes-v7.2-rc7' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13a31079580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c44651ea7dd2f307
dashboard link: https://syzkaller.appspot.com/bug?extid=b320a4d5f65a61dbbf89
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16b76149580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b320a4d5f65a61dbbf89 at syzkaller.appspotmail.com

Oops: divide error: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 6029 Comm: syz-executor518 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:add_device drivers/mtd/devices/block2mtd.c:296 [inline]
RIP: 0010:block2mtd_setup2.isra.0+0x3c8/0xc70 drivers/mtd/devices/block2mtd.c:459
Code: 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 2b 08 00 00 48 8b 6d 08 31 ff 48 89 e8 48 c1 e0 09 48 99 <49> f7 ff 48 89 d6 48 89 54 24 10 e8 98 d5 4d fb 48 8b 54 24 10 48
RSP: 0018:ffffc90004ccf9f0 EFLAGS: 00010206
RAX: 0000000000100000 RBX: 1ffff92000999f41 RCX: ffffffff86bc9838
RDX: 0000000000000000 RSI: ffffffff86bc984a RDI: 0000000000000000
RBP: 0000000000000800 R08: 0000000000000005 R09: 000000000000001f
R10: 0000000000000007 R11: 0000000000000000 R12: ffffc90004ccfaa8
R13: 0000000000000000 R14: ffff8880254fe000 R15: 0000000000000000
FS:  000055558148e400(0000) GS:ffff8880d5dec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a8208cda78 CR3: 000000003ad58000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 block2mtd_setup+0xbd/0xd0 drivers/mtd/devices/block2mtd.c:476
 param_attr_store+0x199/0x300 kernel/params.c:589
 module_attr_store+0x58/0x80 kernel/params.c:904
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0b39a14737
Code: 48 89 fa 4c 89 df e8 98 1d 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffdcc22a9a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055558148e400 RCX: 00007f0b39a14737
RDX: 000000000000000c RSI: 00007ffdcc22aa50 RDI: 0000000000000004
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffdcc22aa50
R13: 00007ffdcc22aa10 R14: 00007ffdcc22a9f0 R15: 0000000000000002
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:add_device drivers/mtd/devices/block2mtd.c:296 [inline]
RIP: 0010:block2mtd_setup2.isra.0+0x3c8/0xc70 drivers/mtd/devices/block2mtd.c:459
Code: 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 2b 08 00 00 48 8b 6d 08 31 ff 48 89 e8 48 c1 e0 09 48 99 <49> f7 ff 48 89 d6 48 89 54 24 10 e8 98 d5 4d fb 48 8b 54 24 10 48
RSP: 0018:ffffc90004ccf9f0 EFLAGS: 00010206
RAX: 0000000000100000 RBX: 1ffff92000999f41 RCX: ffffffff86bc9838
RDX: 0000000000000000 RSI: ffffffff86bc984a RDI: 0000000000000000
RBP: 0000000000000800 R08: 0000000000000005 R09: 000000000000001f
R10: 0000000000000007 R11: 0000000000000000 R12: ffffc90004ccfaa8
R13: 0000000000000000 R14: ffff8880254fe000 R15: 0000000000000000
FS:  000055558148e400(0000) GS:ffff8880d5dec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a8208cda78 CR3: 000000003ad58000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
   7:	fc ff df
   a:	48 89 fa             	mov    %rdi,%rdx
   d:	48 c1 ea 03          	shr    $0x3,%rdx
  11:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
  15:	0f 85 2b 08 00 00    	jne    0x846
  1b:	48 8b 6d 08          	mov    0x8(%rbp),%rbp
  1f:	31 ff                	xor    %edi,%edi
  21:	48 89 e8             	mov    %rbp,%rax
  24:	48 c1 e0 09          	shl    $0x9,%rax
  28:	48 99                	cqto
* 2a:	49 f7 ff             	idiv   %r15 <-- trapping instruction
  2d:	48 89 d6             	mov    %rdx,%rsi
  30:	48 89 54 24 10       	mov    %rdx,0x10(%rsp)
  35:	e8 98 d5 4d fb       	call   0xfb4dd5d2
  3a:	48 8b 54 24 10       	mov    0x10(%rsp),%rdx
  3f:	48                   	rex.W


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