Unable to handle kernel paging request at virtual address ffff8d7fff010008
Current syz.0.79 pgtable: 4K pagesize, 48-bit VAs, pgdp=0x00000000b1bd6000
[ffff8d7fff010008] pgd=000000002299ac01, p4d=000000002299ac01, pud=000000002299bc01, pmd=0000000025a9dc01, pte=0000000000000000
Oops [#1]
Modules linked in:
CPU: 1 UID: 0 PID: 4118 Comm: syz.0.79 Not tainted syzkaller #0 PREEMPT 
Hardware name: riscv-virtio,qemu (DT)
epc : __raw_writeb arch/riscv/include/asm/mmio.h:22 [inline]
epc : _outb include/asm-generic/io.h:635 [inline]
epc : subdev_8255_io+0x27e/0x336 drivers/comedi/drivers/comedi_8255.c:47
 ra : _outb include/asm-generic/io.h:635 [inline]
 ra : subdev_8255_io+0x27a/0x336 drivers/comedi/drivers/comedi_8255.c:47
epc : ffffffff84d96512 ra : ffffffff84d9650e sp : ffff8f800b8877a0
 gp : ffffffff8a2fec60 tp : ffffaf801cfe8000 t0 : ffff8f800b8876d0
 t1 : ffffffff8a40bb00 t2 : ffffffff84d36fae s0 : ffff8f800b8877e0
 s1 : 0000000000000000 a0 : 0000000000000001 a1 : 0000000000000000
 a2 : 0000000000080000 a3 : ffffffff84d9650e a4 : ffff8f8004763dd0
 a5 : 000000000001add0 a6 : 0000000000000003 a7 : 0000000000000001
 s2 : ffff8d7fff010008 s3 : 0000020000000000 s4 : 000000000000009b
 s5 : 0000200000000000 s6 : ffffaf8000000000 s7 : 0000000000000007
 s8 : fffff5ef03a47037 s9 : fffff5ef03a47038 s10: 000000000000001f
 s11: 0000000000000000 t3 : 6486aef400000000 t4 : 0000000000001fff
 t5 : 00000000000000c8 t6 : 0000000000000002
status: 0000000200000120 badaddr: ffff8d7fff010008 cause: 000000000000000f
[<ffffffff84d96512>] _outb include/asm-generic/io.h:635 [inline]
[<ffffffff84d96512>] subdev_8255_io+0x27e/0x336 drivers/comedi/drivers/comedi_8255.c:47
[<ffffffff84d966d2>] subdev_8255_do_config.isra.0+0x108/0x132 drivers/comedi/drivers/comedi_8255.c:115
[<ffffffff84d96d4a>] __subdev_8255_init drivers/comedi/drivers/comedi_8255.c:172 [inline]
[<ffffffff84d96d4a>] subdev_8255_io_init+0x1ec/0x282 drivers/comedi/drivers/comedi_8255.c:192
[<ffffffff84d97342>] dev_8255_attach drivers/comedi/drivers/8255.c:82 [inline]
[<ffffffff84d97342>] dev_8255_attach+0x15a/0x368 drivers/comedi/drivers/8255.c:46
[<ffffffff84d4afc8>] comedi_device_attach+0x364/0x822 drivers/comedi/drivers.c:1069
[<ffffffff84d36688>] do_devconfig_ioctl+0x1b0/0x668 drivers/comedi/comedi_fops.c:928
[<ffffffff84d404a4>] comedi_unlocked_ioctl+0xf62/0x2d94 drivers/comedi/comedi_fops.c:2240
[<ffffffff80cd6f6a>] vfs_ioctl fs/ioctl.c:51 [inline]
[<ffffffff80cd6f6a>] __do_sys_ioctl fs/ioctl.c:597 [inline]
[<ffffffff80cd6f6a>] __se_sys_ioctl fs/ioctl.c:583 [inline]
[<ffffffff80cd6f6a>] __riscv_sys_ioctl+0x180/0x1e4 fs/ioctl.c:583
[<ffffffff800789d8>] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112
[<ffffffff86662f6e>] do_trap_ecall_u+0x3d8/0x56c arch/riscv/kernel/traps.c:343
[<ffffffff8668cf0e>] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198
Code: 9926 995a 0933 4139 c097 fb77 80e7 5a20 0933 4159 (0023) 0149 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	9926                	add	s2,s2,s1
   2:	995a                	add	s2,s2,s6
   4:	41390933          	sub	s2,s2,s3
   8:	fb77c097          	auipc	ra,0xfb77c
   c:	5a2080e7          	jalr	1442(ra) # 0xfb77c5aa
  10:	41590933          	sub	s2,s2,s5
* 14:	01490023          	sb	s4,0(s2) <-- trapping instruction