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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 260f6f4fda93 Merge tag 'drm-next-2025-07-30' of https://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a382a2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7fee18db2e205628
dashboard link: https://syzkaller.appspot.com/bug?extid=c28e542f215838132ac8
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/890ef571e5de/disk-260f6f4f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9b312492ad33/vmlinux-260f6f4f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/337ca5d06cc4/bzImage-260f6f4f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c28e54...@syzkaller.appspotmail.com

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

write to 0xffff88810334f008 of 4 bytes by task 17801 on cpu 0:
__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+0x120/0x390 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+0xba/0xf0 drivers/input/input.c:423
evdev_write+0x1fa/0x290 drivers/input/evdev.c:528
vfs_write+0x269/0x8e0 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 0xffff88810334f008 of 4 bytes by task 2977 on cpu 1:
evdev_read+0x158/0x5e0 drivers/input/evdev.c:572
vfs_read+0x19d/0x6f0 fs/read_write.c:570
ksys_read+0xda/0x1a0 fs/read_write.c:715
__do_sys_read fs/read_write.c:724 [inline]
__se_sys_read fs/read_write.c:722 [inline]
__x64_sys_read+0x40/0x50 fs/read_write.c:722
x64_sys_call+0x27bc/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:1
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: 0x0000003e -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2977 Comm: acpid Not tainted 6.16.0-syzkaller-08685-g260f6f4fda93 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.