syzbot

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BUG: KCSAN: data-race in sock_alloc_send_pskb / unix_release_sock

write to 0xffff888125dcf66a of 1 bytes by task 16479 on cpu 0:
 unix_release_sock+0x25e/0x650 net/unix/af_unix.c:548
 unix_release+0x2f/0x50 net/unix/af_unix.c:867
 __sock_release net/socket.c:605 [inline]
 sock_close+0x6c/0x150 net/socket.c:1278
 __fput+0x1df/0x460 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:135
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:239 [inline]
 __prepare_exit_to_usermode+0x1c6/0x230 arch/x86/entry/common.c:269
 __syscall_return_slowpath+0x47/0x60 arch/x86/entry/common.c:352
 do_syscall_64+0x5d/0xb0 arch/x86/entry/common.c:393
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888125dcf66a of 1 bytes by task 16480 on cpu 1:
 sock_alloc_send_pskb+0x105/0x470 net/core/sock.c:2341
 unix_dgram_sendmsg+0x48a/0x1500 net/unix/af_unix.c:1679
 unix_seqpacket_sendmsg+0xc2/0x100 net/unix/af_unix.c:2063
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2352
 ___sys_sendmsg net/socket.c:2406 [inline]
 __sys_sendmmsg+0x322/0x4b0 net/socket.c:2496
 __do_sys_sendmmsg net/socket.c:2525 [inline]
 __se_sys_sendmmsg net/socket.c:2522 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2522
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16480 Comm: syz-executor.4 Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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