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BUG: KCSAN: data-race in packet_rcv / packet_setsockopt

write to 0xffff88811f7794bc of 1 bytes by task 22059 on cpu 0:
 packet_setsockopt+0xb47/0x1fc0 net/packet/af_packet.c:3816
 __sys_setsockopt+0x27a/0x390 net/socket.c:2127
 __do_sys_setsockopt net/socket.c:2143 [inline]
 __se_sys_setsockopt net/socket.c:2140 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2140
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811f7794bc of 1 bytes by task 22073 on cpu 1:
 packet_rcv+0x4ab/0xa70 net/packet/af_packet.c:2112
 deliver_skb net/core/dev.c:2247 [inline]
 __netif_receive_skb_core+0x43a/0x1da0 net/core/dev.c:5132
 __netif_receive_skb_one_core net/core/dev.c:5279 [inline]
 __netif_receive_skb+0x52/0x1b0 net/core/dev.c:5395
 netif_receive_skb_internal+0x3a/0x130 net/core/dev.c:5497
 netif_receive_skb+0x1b/0x1d0 net/core/dev.c:5556
 tun_rx_batched drivers/net/tun.c:1518 [inline]
 tun_get_user+0x1c2c/0x1e30 drivers/net/tun.c:1972
 tun_chr_write_iter+0xb0/0x100 drivers/net/tun.c:2001
 call_write_iter include/linux/fs.h:1908 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x607/0x690 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 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: 22073 Comm: syz-executor.0 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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