syzbot

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BUG: KCSAN: data-race in fasync_remove_entry / sock_wake_async

write to 0xffff8881005a4398 of 8 bytes by task 6044 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:1416
 __fput+0x5e6/0x650 fs/file_table.c:462
 ____fput+0x1c/0x30 fs/file_table.c:493
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work+0x6a/0x70 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x77/0xb0 kernel/entry/common.c:218
 do_syscall_64+0xdd/0x1a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881005a4398 of 8 bytes by task 6042 on cpu 0:
 sock_wake_async+0x29/0x110 net/socket.c:1431
 sk_wake_async_rcu include/net/sock.h:2505 [inline]
 unix_write_space+0x13b/0x140 net/unix/af_unix.c:604
 sock_wfree+0x14b/0x3c0 net/core/sock.c:2629
 unix_destruct_scm+0xc3/0xf0 net/unix/af_unix.c:1869
 skb_release_head_state+0xb7/0x1a0 net/core/skbuff.c:1149
 skb_release_all net/core/skbuff.c:1160 [inline]
 __kfree_skb+0x18/0x150 net/core/skbuff.c:1176
 sk_skb_reason_drop+0xbd/0x270 net/core/skbuff.c:1214
 kfree_skb_reason include/linux/skbuff.h:1279 [inline]
 unix_release_sock+0x5d3/0x720 net/unix/af_unix.c:712
 unix_release+0x58/0x80 net/unix/af_unix.c:1097
 __sock_release net/socket.c:647 [inline]
 sock_close+0x6b/0x150 net/socket.c:1391
 __fput+0x29b/0x650 fs/file_table.c:465
 ____fput+0x1c/0x30 fs/file_table.c:493
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work+0x6a/0x70 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x77/0xb0 kernel/entry/common.c:218
 do_syscall_64+0xdd/0x1a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811925f2a0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6042 Comm: syz.2.840 Not tainted 6.15.0-rc6-syzkaller-00105-g088d13246a46 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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