syzbot

batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
==================================================================
BUG: KCSAN: data-race in batadv_check_known_mac_addr / batadv_iv_ogm_schedule

write to 0xffff88802830c210 of 1 bytes by task 9795 on cpu 1:
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:803 [inline]
 batadv_iv_ogm_schedule+0xb3/0x7b0 net/batman-adv/bat_iv_ogm.c:869
 batadv_iv_send_outstanding_bat_ogm_packet+0x428/0x480 net/batman-adv/bat_iv_ogm.c:1723
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x635/0xb90 kernel/workqueue.c:2421
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88802830c210 of 1 bytes by task 8455 on cpu 0:
 batadv_check_known_mac_addr+0x59/0x190 net/batman-adv/hard-interface.c:504
 batadv_hard_if_event+0x4ce/0xd90 net/batman-adv/hard-interface.c:1026
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0x53/0xb0 kernel/notifier.c:410
 call_netdevice_notifiers_info net/core/dev.c:2040 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2052 [inline]
 call_netdevice_notifiers net/core/dev.c:2066 [inline]
 dev_set_mac_address+0x1d0/0x270 net/core/dev.c:8739
 do_setlink+0x45a/0x21d0 net/core/rtnetlink.c:2663
 __rtnl_newlink net/core/rtnetlink.c:3376 [inline]
 rtnl_newlink+0xe58/0x12f0 net/core/rtnetlink.c:3491
 rtnetlink_rcv_msg+0x723/0x7c0 net/core/rtnetlink.c:5553
 netlink_rcv_skb+0x13e/0x240 net/netlink/af_netlink.c:2494
 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5571
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x5df/0x6b0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x6f8/0x7c0 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 __sys_sendto+0x2a8/0x370 net/socket.c:1975
 __do_sys_sendto net/socket.c:1987 [inline]
 __se_sys_sendto net/socket.c:1983 [inline]
 __x64_sys_sendto+0x74/0x90 net/socket.c:1983
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8455 Comm: syz-executor.4 Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================