[moderation] [input?] KCSAN: data-race in __ps2_command / ps2_interrupt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 48a5a7ab8d6a Merge tag 'v7.2-rc4-smb3-client-fixes' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=109522a9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=1ecceabfed79f6a96c7d
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [dmitry....@gmail.com linux...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f80e802da100/disk-48a5a7ab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c52d5cfe5b19/vmlinux-48a5a7ab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/117a746cd695/bzImage-48a5a7ab.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1eccea...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __ps2_command / ps2_interrupt

write to 0xffff888103855058 of 1 bytes by interrupt on cpu 0:
ps2_handle_response drivers/input/serio/libps2.c:479 [inline]
ps2_interrupt+0x1be/0x550 drivers/input/serio/libps2.c:608
serio_interrupt+0x66/0xf0 drivers/input/serio/serio.c:967
i8042_handle_data+0x388/0x680 drivers/input/serio/i8042.c:598
i8042_interrupt+0x15/0x90 drivers/input/serio/i8042.c:605
__handle_irq_event_percpu+0x8b/0x480 kernel/irq/handle.c:209
handle_irq_event_percpu kernel/irq/handle.c:246 [inline]
handle_irq_event+0x64/0xf0 kernel/irq/handle.c:263
handle_edge_irq+0x155/0x440 kernel/irq/chip.c:859
generic_handle_irq_desc include/linux/irqdesc.h:188 [inline]
handle_irq arch/x86/kernel/irq.c:209 [inline]
call_irq_handler arch/x86/kernel/irq.c:-1 [inline]
__common_interrupt+0x60/0xb0 arch/x86/kernel/irq.c:280
common_interrupt+0x7e/0x90 arch/x86/kernel/irq.c:273
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665
kcsan_setup_watchpoint+0x3e8/0x450 kernel/kcsan/core.c:705
follow_page_pte+0x45/0x970 mm/gup.c:808
follow_pmd_mask mm/gup.c:915 [inline]
follow_pud_mask mm/gup.c:967 [inline]
follow_p4d_mask mm/gup.c:984 [inline]
follow_page_mask mm/gup.c:1023 [inline]
__get_user_pages+0x801/0x1f10 mm/gup.c:1426
populate_vma_page_range mm/gup.c:1860 [inline]
__mm_populate+0x242/0x390 mm/gup.c:1963
mm_populate include/linux/mm.h:4171 [inline]
vm_mmap_pgoff+0x23b/0x2d0 mm/util.c:586
ksys_mmap_pgoff+0xc1/0x310 mm/mmap.c:606
x64_sys_call+0x14df/0x3020 arch/x86/include/generated/asm/syscalls_64.h:10
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103855058 of 1 bytes by task 3407 on cpu 1:
__ps2_command+0x591/0xaa0 drivers/input/serio/libps2.c:343
ps2_command+0x52/0x90 drivers/input/serio/libps2.c:403
synaptics_detect+0x8e/0x130 drivers/input/mouse/synaptics.c:105
psmouse_do_detect drivers/input/mouse/psmouse-base.c:987 [inline]
psmouse_extensions+0x4df/0x960 drivers/input/mouse/psmouse-base.c:1082
__psmouse_reconnect+0x3da/0x8b0 drivers/input/mouse/psmouse-base.c:1685
psmouse_reconnect+0x17/0x20 drivers/input/mouse/psmouse-base.c:1723
serio_reconnect_driver drivers/input/serio/serio.c:52 [inline]
serio_reconnect_port drivers/input/serio/serio.c:558 [inline]
serio_handle_event+0x1c7/0xac0 drivers/input/serio/serio.c:201
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
worker_thread+0x569/0x750 kernel/workqueue.c:3486
kthread+0x221/0x270 kernel/kthread.c:436
ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3407 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: events_long serio_handle_event
==================================================================


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