Re: [syzbot] [block?] WARNING in floppy_interrupt (2)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    1ef6663a587b Merge tag 'tag-chrome-platform-for-v6.5' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124a5670a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=319f18de2a0a8640
dashboard link: https://syzkaller.appspot.com/bug?extid=aa45f3927a085bc1b242
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=127d41e0a80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=145f1ee0a80000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-1ef6663a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1600540a0cdf/vmlinux-1ef6663a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/36ac12d50d01/bzImage-1ef6663a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aa45f3927a085bc1b242@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
WARNING: CPU: 1 PID: 4921 at drivers/block/floppy.c:999 schedule_bh drivers/block/floppy.c:999 [inline]
WARNING: CPU: 1 PID: 4921 at drivers/block/floppy.c:999 floppy_interrupt+0x3cc/0x440 drivers/block/floppy.c:1765
Modules linked in:
CPU: 1 PID: 4921 Comm: kworker/u16:2 Not tainted 6.4.0-syzkaller-01224-g1ef6663a587b #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Workqueue: floppy floppy_work_workfn
RIP: 0010:schedule_bh drivers/block/floppy.c:999 [inline]
RIP: 0010:floppy_interrupt+0x3cc/0x440 drivers/block/floppy.c:1765
Code: 4d d0 8a 89 c6 89 05 73 c4 ea 0c e8 8e 27 ff ff 8b 1d 68 c4 ea 0c e9 9c fd ff ff e8 ce 56 b1 fc e9 66 fd ff ff e8 24 67 5f fc <0f> 0b e9 c9 fe ff ff 48 c7 c7 00 f2 40 8c e8 71 56 b1 fc e9 5a fc
RSP: 0018:ffffc90000aa8e58 EFLAGS: 00010046
RAX: 0000000080010000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff888031a98800 RSI: ffffffff852425ac RDI: 0000000000000001
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffffc90000aa8ff8 R12: ffffffff85239f60
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000006
FS:  0000000000000000(0000) GS:ffff88806b700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cd072ef000 CR3: 000000000c571000 CR4: 0000000000350ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 floppy_hardint+0x1b1/0x200 arch/x86/include/asm/floppy.h:66
 __handle_irq_event_percpu+0x22b/0x730 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
 handle_edge_irq+0x263/0xd00 kernel/irq/chip.c:834
 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
 handle_irq arch/x86/kernel/irq.c:238 [inline]
 __common_interrupt+0xa1/0x220 arch/x86/kernel/irq.c:257
 common_interrupt+0xa8/0xd0 arch/x86/kernel/irq.c:247
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636
RIP: 0010:outb_p arch/x86/include/asm/io.h:296 [inline]
RIP: 0010:fdc_outb drivers/block/floppy.c:602 [inline]
RIP: 0010:reset_fdc+0x185/0x400 drivers/block/floppy.c:1817
Code: ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 80 3c 11 00 0f 85 8a 01 00 00 48 8d 14 9b 48 8b 14 d5 f0 c0 0e 92 83 c2 04 ee <e8> 56 ec ff ff 48 83 c4 08 5b 5d e9 9b 1f 60 fc e8 96 1f 60 fc 48
RSP: 0018:ffffc9000308fc70 EFLAGS: 00000202
RAX: 00000000ffffff81 RBX: 0000000000000000 RCX: 1ffffffff241d81e
RDX: 00000000000003f4 RSI: ffffffff85236c9c RDI: ffffffff920ec0f0
RBP: 0000000000000062 R08: 0000000000000001 R09: 0000000000000044
R10: 0000000000000062 R11: 0000000032393454 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000020 R15: 0000ffff88800010
 floppy_ready+0x67c/0x1b60 drivers/block/floppy.c:1929
 redo_format+0x545/0x6f0 drivers/block/floppy.c:2214
 process_one_work+0x99a/0x15e0 kernel/workqueue.c:2408
 worker_thread+0x67d/0x10c0 kernel/workqueue.c:2555
 kthread+0x344/0x440 kernel/kthread.c:379
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>
----------------
Code disassembly (best guess):
   0:	ba 00 00 00 00       	mov    $0x0,%edx
   5:	00 fc                	add    %bh,%ah
   7:	ff                   	(bad)
   8:	df 48 89             	fisttps -0x77(%rax)
   b:	f9                   	stc
   c:	48 c1 e9 03          	shr    $0x3,%rcx
  10:	80 3c 11 00          	cmpb   $0x0,(%rcx,%rdx,1)
  14:	0f 85 8a 01 00 00    	jne    0x1a4
  1a:	48 8d 14 9b          	lea    (%rbx,%rbx,4),%rdx
  1e:	48 8b 14 d5 f0 c0 0e 	mov    -0x6df13f10(,%rdx,8),%rdx
  25:	92
  26:	83 c2 04             	add    $0x4,%edx
  29:	ee                   	out    %al,(%dx)
* 2a:	e8 56 ec ff ff       	callq  0xffffec85 <-- trapping instruction
  2f:	48 83 c4 08          	add    $0x8,%rsp
  33:	5b                   	pop    %rbx
  34:	5d                   	pop    %rbp
  35:	e9 9b 1f 60 fc       	jmpq   0xfc601fd5
  3a:	e8 96 1f 60 fc       	callq  0xfc601fd5
  3f:	48                   	rex.W


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