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BUG: KCSAN: data-race in netlink_deliver_tap / netlink_setsockopt

read to 0xffff8880a0edfb04 of 4 bytes by task 31305 on cpu 1:
 netlink_is_kernel net/netlink/af_netlink.c:82 [inline]
 __netlink_deliver_tap_skb net/netlink/af_netlink.c:291 [inline]
 __netlink_deliver_tap net/netlink/af_netlink.c:312 [inline]
 netlink_deliver_tap+0x350/0x4a0 net/netlink/af_netlink.c:325
 __netlink_sendskb+0x41/0x80 net/netlink/af_netlink.c:1246
 netlink_dump+0x453/0x800 net/netlink/af_netlink.c:2255
 __netlink_dump_start+0x402/0x530 net/netlink/af_netlink.c:2352
 netlink_dump_start include/linux/netlink.h:233 [inline]
 rtnetlink_rcv_msg+0x3d2/0x500 net/core/rtnetlink.c:5387
 netlink_rcv_skb+0xb0/0x260 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x26/0x30 net/core/rtnetlink.c:5442
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x3a6/0x4d0 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x4d3/0x8b0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:639 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:659
 sock_write_iter+0x16b/0x210 net/socket.c:991
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write+0x388/0x4a0 fs/read_write.c:483
 __vfs_write+0xb1/0xc0 fs/read_write.c:496
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0x17b/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880a0edfb04 of 4 bytes by task 31303 on cpu 0:
 netlink_setsockopt+0x47b/0x750 net/netlink/af_netlink.c:1711
 __sys_setsockopt+0x1ce/0x370 net/socket.c:2117
 __do_sys_setsockopt net/socket.c:2133 [inline]
 __se_sys_setsockopt net/socket.c:2130 [inline]
 __x64_sys_setsockopt+0x70/0x90 net/socket.c:2130
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31303 Comm: syz-executor.1 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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