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BUG: KCSAN: data-race in batadv_hard_if_event / batadv_mcast_mla_update

write to 0xffff888165814810 of 1 bytes by task 11281 on cpu 1:
 batadv_hardif_remove_interface net/batman-adv/hard-interface.c:930 [inline]
 batadv_hard_if_event+0x896/0xfb0 net/batman-adv/hard-interface.c:988
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2206
 call_netdevice_notifiers_extack net/core/dev.c:2244 [inline]
 call_netdevice_notifiers net/core/dev.c:2258 [inline]
 unregister_netdevice_many_notify+0x99b/0x1290 net/core/dev.c:11887
 unregister_netdevice_many+0x19/0x20 net/core/dev.c:11951
 rtnl_newlink_create+0x452/0x5e0 net/core/rtnetlink.c:3824
 __rtnl_newlink net/core/rtnetlink.c:3907 [inline]
 rtnl_newlink+0xeea/0x1280 net/core/rtnetlink.c:4022
 rtnetlink_rcv_msg+0x65a/0x740 net/core/rtnetlink.c:6912
 netlink_rcv_skb+0x12f/0x230 net/netlink/af_netlink.c:2533
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6939
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x605/0x6c0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x609/0x720 net/netlink/af_netlink.c:1882
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:733
 ____sys_sendmsg+0x350/0x4e0 net/socket.c:2573
 ___sys_sendmsg net/socket.c:2627 [inline]
 __sys_sendmsg+0x1a0/0x240 net/socket.c:2659
 __do_sys_sendmsg net/socket.c:2664 [inline]
 __se_sys_sendmsg net/socket.c:2662 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2662
 x64_sys_call+0x26f3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888165814810 of 1 bytes by task 7538 on cpu 0:
 batadv_mcast_mla_forw_flags_get net/batman-adv/multicast.c:252 [inline]
 batadv_mcast_mla_flags_get net/batman-adv/multicast.c:289 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:909 [inline]
 batadv_mcast_mla_update+0x21d/0x1710 net/batman-adv/multicast.c:948
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3400
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7538 Comm: kworker/u8:14 Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: bat_events batadv_mcast_mla_update
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