[moderation] [input?] KCSAN: data-race in evdev_pass_values / evdev_poll (12)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 39f90c196721 Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15d25462580000
kernel config: https://syzkaller.appspot.com/x/.config?x=86a2212b48ce4ce2
dashboard link: https://syzkaller.appspot.com/bug?extid=cb962545025ba25fcb26
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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/d7e6adef211e/disk-39f90c19.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b91130e58c7a/vmlinux-39f90c19.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cf89a7b36b34/bzImage-39f90c19.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cb9625...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in evdev_pass_values / evdev_poll

write to 0xffff888100378008 of 4 bytes by task 5994 on cpu 1:
__pass_event drivers/input/evdev.c:239 [inline]
evdev_pass_values+0x3d4/0x510 drivers/input/evdev.c:278
evdev_events+0x8e/0xd0 drivers/input/evdev.c:306
input_pass_values+0x123/0x390 drivers/input/input.c:127
input_event_dispose+0x248/0x320 drivers/input/input.c:341
input_handle_event+0x9e8/0xa20 drivers/input/input.c:369
input_inject_event+0xbc/0x120 drivers/input/input.c:423
evdev_write+0x1fa/0x290 drivers/input/evdev.c:528
vfs_write+0x269/0x960 fs/read_write.c:684
ksys_write+0xda/0x1a0 fs/read_write.c:738
__do_sys_write fs/read_write.c:749 [inline]
__se_sys_write fs/read_write.c:746 [inline]
__x64_sys_write+0x40/0x50 fs/read_write.c:746
x64_sys_call+0x27fe/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100378008 of 4 bytes by task 2977 on cpu 0:
evdev_poll+0xc4/0x100 drivers/input/evdev.c:621
vfs_poll include/linux/poll.h:82 [inline]
select_poll_one fs/select.c:480 [inline]
do_select+0x8ee/0xf50 fs/select.c:536
core_sys_select+0x3d7/0x6e0 fs/select.c:677
do_pselect fs/select.c:759 [inline]
__do_sys_pselect6 fs/select.c:802 [inline]
__se_sys_pselect6+0x216/0x280 fs/select.c:793
__x64_sys_pselect6+0x78/0x90 fs/select.c:793
x64_sys_call+0x28b9/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:271
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000002 -> 0x00000005

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2977 Comm: acpid Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
==================================================================


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