syzbot

batman_adv: batadv0: Interface activated: batadv_slave_0
==================================================================
BUG: KCSAN: data-race in batadv_iv_ogm_schedule / batadv_update_min_mtu

write to 0xffff88811777f610 of 1 bytes by task 3408 on cpu 1:
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:811 [inline]
 batadv_iv_ogm_schedule+0xab/0x740 net/batman-adv/bat_iv_ogm.c:876
 batadv_iv_send_outstanding_bat_ogm_packet+0x419/0x470 net/batman-adv/bat_iv_ogm.c:1720
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x486/0x510 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

read to 0xffff88811777f610 of 1 bytes by task 3314 on cpu 0:
 batadv_hardif_min_mtu net/batman-adv/hard-interface.c:593 [inline]
 batadv_update_min_mtu+0x45/0x1a0 net/batman-adv/hard-interface.c:640
 batadv_hardif_activate_interface+0x1b3/0x2f0 net/batman-adv/hard-interface.c:680
 batadv_hard_if_event+0x3b3/0x1070 net/batman-adv/hard-interface.c:975
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2176
 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
 call_netdevice_notifiers net/core/dev.c:2228 [inline]
 __dev_notify_flags+0xff/0x1a0 net/core/dev.c:-1
 netif_change_flags+0xac/0xd0 net/core/dev.c:9422
 do_setlink+0x90e/0x27f0 net/core/rtnetlink.c:3152
 rtnl_changelink net/core/rtnetlink.c:3769 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
 rtnl_newlink+0xe75/0x12d0 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2534
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6982
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x5a1/0x670 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:727
 __sys_sendto+0x268/0x330 net/socket.c:2180
 __do_sys_sendto net/socket.c:2187 [inline]
 __se_sys_sendto net/socket.c:2183 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2183
 x64_sys_call+0x2eb6/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x04 -> 0x03

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3314 Comm: syz-executor Not tainted 6.15.0-rc6-syzkaller-00346-g5723cc3450bc #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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batman_adv: batadv0: Interface activated: batadv_slave_1
netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0