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syzbot reports a case of ethtool_ops->get_link being called without ops lock: ethtool_op_get_link+0x15/0x60 net/ethtool/ioctl.c:63 bond_check_dev_link+0x1fb/0x4b0 drivers/net/bonding/bond_main.c:864 bond_miimon_inspect drivers/net/bonding/bond_main.c:2734 [inline] bond_mii_monitor+0x49d/0x3170 drivers/net/bonding/bond_main.c:2956 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd50 kernel/workqueue.c:3400 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Commit 04efcee6ef8d ("net: hold instance lock during NETDEV_CHANGE") changed to lockless __linkwatch_sync_dev in ethtool_op_get_link. All paths except bonding are coming via locked ioctl. Add necessary locking to bonding. Reviewed-by: Hangbin Liu <liuhangbin@gmail.com> Reported-by: syzbot+48c14f61594bdfadb086@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=48c14f61594bdfadb086 Fixes: 04efcee6ef8d ("net: hold instance lock during NETDEV_CHANGE") Signed-off-by: Stanislav Fomichev <sdf@fomichev.me> Link: https://patch.msgid.link/20250410161117.3519250-1-sdf@fomichev.me Signed-off-by: Jakub Kicinski <kuba@kernel.org>