[syzbot] [usb?] [input?] KMSAN: uninit-value in steam_register

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8e65320d91cd Merge tag 'drm-fixes-2026-06-06' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13cb9e7a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a0ca3b8cb3875012
dashboard link: https://syzkaller.appspot.com/bug?extid=75f3f9bff8c510602d36
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/793bd3b9425c/disk-8e65320d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4bfe5cfc266c/vmlinux-8e65320d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/99c7cd705a06/bzImage-8e65320d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+75f3f9...@syzkaller.appspotmail.com

hid-steam 0003:28DE:1102.0007: unknown main item tag 0x0
hid-steam 0003:28DE:1102.0007: unknown main item tag 0x0
hid-steam 0003:28DE:1102.0007: : USB HID v7f.fd Device [HID 28de:1102] on usb-dummy_hcd.1-1/input0
=====================================================
BUG: KMSAN: uninit-value in steam_get_serial drivers/hid/hid-steam.c:457 [inline]
BUG: KMSAN: uninit-value in steam_register+0xd83/0x10e0 drivers/hid/hid-steam.c:965
steam_get_serial drivers/hid/hid-steam.c:457 [inline]
steam_register+0xd83/0x10e0 drivers/hid/hid-steam.c:965
steam_probe+0x6f1/0x19b0 drivers/hid/hid-steam.c:1273
__hid_device_probe drivers/hid/hid-core.c:2822 [inline]
hid_device_probe+0x60d/0xb90 drivers/hid/hid-core.c:2859
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d5/0xe40 drivers/base/dd.c:709
__driver_probe_device+0x2fb/0x410 drivers/base/dd.c:871
driver_probe_device+0x70/0x8f0 drivers/base/dd.c:901
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:1029
bus_for_each_drv+0x3e3/0x680 drivers/base/bus.c:500
__device_attach+0x3c5/0x5f0 drivers/base/dd.c:1101
device_initial_probe+0x126/0x170 drivers/base/dd.c:1156
bus_probe_device+0x287/0x530 drivers/base/bus.c:613
device_add+0x12e3/0x1c90 drivers/base/core.c:3706
hid_add_device+0x440/0x5d0 drivers/hid/hid-core.c:3003
usbhid_probe+0x1a25/0x20e0 drivers/hid/usbhid/hid-core.c:1449
usb_probe_interface+0xd51/0x1440 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d5/0xe40 drivers/base/dd.c:709
__driver_probe_device+0x2fb/0x410 drivers/base/dd.c:871
driver_probe_device+0x70/0x8f0 drivers/base/dd.c:901
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:1029
bus_for_each_drv+0x3e3/0x680 drivers/base/bus.c:500
__device_attach+0x3c5/0x5f0 drivers/base/dd.c:1101
device_initial_probe+0x126/0x170 drivers/base/dd.c:1156
bus_probe_device+0x287/0x530 drivers/base/bus.c:613
device_add+0x12e3/0x1c90 drivers/base/core.c:3706
usb_set_configuration+0x3484/0x3b60 drivers/usb/core/message.c:2268
usb_generic_driver_probe+0xfc/0x290 drivers/usb/core/generic.c:250
usb_probe_device+0x38d/0x690 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d5/0xe40 drivers/base/dd.c:709
__driver_probe_device+0x2fb/0x410 drivers/base/dd.c:871
driver_probe_device+0x70/0x8f0 drivers/base/dd.c:901
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:1029
bus_for_each_drv+0x3e3/0x680 drivers/base/bus.c:500
__device_attach+0x3c5/0x5f0 drivers/base/dd.c:1101
device_initial_probe+0x126/0x170 drivers/base/dd.c:1156
bus_probe_device+0x287/0x530 drivers/base/bus.c:613
device_add+0x12e3/0x1c90 drivers/base/core.c:3706
usb_new_device+0x106a/0x2120 drivers/usb/core/hub.c:2695
hub_port_connect drivers/usb/core/hub.c:5567 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
port_event drivers/usb/core/hub.c:5871 [inline]
hub_event+0x5404/0x77c0 drivers/usb/core/hub.c:5953
process_one_work kernel/workqueue.c:3314 [inline]
process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3397
worker_thread+0xee4/0x1590 kernel/workqueue.c:3478
kthread+0x53a/0x5f0 kernel/kthread.c:436
ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Local variable reply.i created at:
steam_get_serial drivers/hid/hid-steam.c:448 [inline]
steam_register+0x180/0x10e0 drivers/hid/hid-steam.c:965
steam_probe+0x6f1/0x19b0 drivers/hid/hid-steam.c:1273

CPU: 0 UID: 0 PID: 7403 Comm: kworker/0:6 Tainted: G L syzkaller #0 PREEMPT(lazy)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: usb_hub_wq hub_event
=====================================================


---
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