[syzbot] [kernel?] KMSAN: uninit-value in dt2817_dio_insn_bits

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a79a588fc176 Merge tag 'pm-6.16-rc5' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10e62582580000
kernel config: https://syzkaller.appspot.com/x/.config?x=aa9af7332485152e
dashboard link: https://syzkaller.appspot.com/bug?extid=cb96ec476fb4914445c9
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b7cf1187020f/disk-a79a588f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/47e08d61ef4b/vmlinux-a79a588f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/75d3bcd3c8e0/bzImage-a79a588f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cb96ec...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in __outb arch/x86/include/asm/shared/io.h:22 [inline]
BUG: KMSAN: uninit-value in dt2817_dio_insn_bits+0x42d/0x4b0 drivers/comedi/drivers/dt2817.c:82
__outb arch/x86/include/asm/shared/io.h:22 [inline]
dt2817_dio_insn_bits+0x42d/0x4b0 drivers/comedi/drivers/dt2817.c:82
insn_rw_emulate_bits+0x3a6/0x560 drivers/comedi/drivers.c:632
parse_insn+0x14b0/0x1780 drivers/comedi/comedi_fops.c:-1
do_insnlist_ioctl+0x412/0x890 drivers/comedi/comedi_fops.c:1568
comedi_unlocked_ioctl+0x1c6b/0x1e00 drivers/comedi/comedi_fops.c:2253
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0x23c/0x400 fs/ioctl.c:893
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:893
x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
comedi_dio_update_state+0x244/0x250 drivers/comedi/drivers.c:392
dt2817_dio_insn_bits+0x6e/0x4b0 drivers/comedi/drivers/dt2817.c:79
insn_rw_emulate_bits+0x3a6/0x560 drivers/comedi/drivers.c:632
parse_insn+0x14b0/0x1780 drivers/comedi/comedi_fops.c:-1
do_insnlist_ioctl+0x412/0x890 drivers/comedi/comedi_fops.c:1568
comedi_unlocked_ioctl+0x1c6b/0x1e00 drivers/comedi/comedi_fops.c:2253
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0x23c/0x400 fs/ioctl.c:893
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:893
x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
insn_rw_emulate_bits+0x52d/0x560 drivers/comedi/drivers.c:629
parse_insn+0x14b0/0x1780 drivers/comedi/comedi_fops.c:-1
do_insnlist_ioctl+0x412/0x890 drivers/comedi/comedi_fops.c:1568
comedi_unlocked_ioctl+0x1c6b/0x1e00 drivers/comedi/comedi_fops.c:2253
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0x23c/0x400 fs/ioctl.c:893
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:893
x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4154 [inline]
slab_alloc_node mm/slub.c:4197 [inline]
__do_kmalloc_node mm/slub.c:4327 [inline]
__kmalloc_noprof+0x95f/0x1310 mm/slub.c:4340
kmalloc_noprof include/linux/slab.h:909 [inline]
kmalloc_array_noprof include/linux/slab.h:948 [inline]
do_insnlist_ioctl+0x1b2/0x890 drivers/comedi/comedi_fops.c:1551
comedi_unlocked_ioctl+0x1c6b/0x1e00 drivers/comedi/comedi_fops.c:2253
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0x23c/0x400 fs/ioctl.c:893
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:893
x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 6184 Comm: syz.4.49 Not tainted 6.16.0-rc4-syzkaller-00308-ga79a588fc176 #0 PREEMPT(undef)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
=====================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup