syzbot

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BUG: KCSAN: data-race in fasync_remove_entry / kill_fasync

write to 0xffff8881005b7458 of 8 bytes by task 29140 on cpu 1:
 fasync_remove_entry+0xcc/0x120 fs/fcntl.c:1005
 fasync_helper+0x97/0xc0 fs/fcntl.c:1104
 sock_fasync+0x58/0xc0 net/socket.c:1464
 __fput+0x5e3/0x650 fs/file_table.c:465
 ____fput+0x1c/0x30 fs/file_table.c:496
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe4/0x100 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881005b7458 of 8 bytes by task 29138 on cpu 0:
 kill_fasync+0x22/0x170 fs/fcntl.c:1146
 sock_wake_async+0xed/0x110 net/socket.c:-1
 sk_wake_async include/net/sock.h:2519 [inline]
 unix_release_sock+0x4b5/0x790 net/unix/af_unix.c:712
 unix_release+0x58/0x80 net/unix/af_unix.c:1196
 __sock_release net/socket.c:649 [inline]
 sock_close+0x68/0x150 net/socket.c:1439
 __fput+0x298/0x650 fs/file_table.c:468
 ____fput+0x1c/0x30 fs/file_table.c:496
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe4/0x100 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888118e02bd0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 29138 Comm: syz.6.8798 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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