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BUG: KCSAN: data-race in netlink_overrun / sock_getsockopt

write to 0xffff8880aebb1a30 of 4 bytes by task 9361 on cpu 0:
 netlink_overrun+0x71/0xb0 net/netlink/af_netlink.c:344
 netlink_attachskb+0x330/0x3f0 net/netlink/af_netlink.c:1214
 netlink_unicast+0x170/0x430 net/netlink/af_netlink.c:1337
 netlink_ack+0x38b/0x680 net/netlink/af_netlink.c:2447
 netlink_rcv_skb+0x22a/0x260 net/netlink/af_netlink.c:2483
 rtnetlink_rcv+0x26/0x30 net/core/rtnetlink.c:5242
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x354/0x430 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x456/0x770 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:657
 __sys_sendto+0x21f/0x320 net/socket.c:1952
 __do_sys_sendto net/socket.c:1964 [inline]
 __se_sys_sendto net/socket.c:1960 [inline]
 __x64_sys_sendto+0x89/0xb0 net/socket.c:1960
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880aebb1a30 of 4 bytes by task 9365 on cpu 1:
 sock_error include/net/sock.h:2167 [inline]
 sock_getsockopt+0xd79/0x1073 net/core/sock.c:1287
 __sys_getsockopt+0x201/0x210 net/socket.c:2125
 __do_sys_getsockopt net/socket.c:2144 [inline]
 __se_sys_getsockopt net/socket.c:2141 [inline]
 __x64_sys_getsockopt+0x70/0x90 net/socket.c:2141
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9365 Comm: syz-executor.5 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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