syzbot

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BUG: KCSAN: data-race in ip6_output / rt6_disable_ip

write to 0xffff88812ae78800 of 8 bytes by task 6529 on cpu 1:
 rt6_uncached_list_flush_dev net/ipv6/route.c:184 [inline]
 rt6_disable_ip+0x2ee/0x580 net/ipv6/route.c:5010
 addrconf_ifdown+0xa6/0xf30 net/ipv6/addrconf.c:3857
 addrconf_notify+0x222/0x930 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6c/0x1b0 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2230
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 dev_close_many+0x170/0x240 net/core/dev.c:1785
 unregister_netdevice_many_notify+0x441/0x1690 net/core/dev.c:12047
 unregister_netdevice_many+0x19/0x20 net/core/dev.c:12140
 ops_exit_rtnl_list net/core/net_namespace.c:188 [inline]
 ops_undo_list+0x213/0x410 net/core/net_namespace.c:249
 cleanup_net+0x2de/0x4d0 net/core/net_namespace.c:686
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3321
 worker_thread+0x582/0x770 kernel/workqueue.c:3402
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88812ae78800 of 8 bytes by task 4085 on cpu 0:
 ip6_output+0x46/0x240 net/ipv6/ip6_output.c:235
 dst_output include/net/dst.h:459 [inline]
 NF_HOOK include/linux/netfilter.h:317 [inline]
 mld_sendpack+0x427/0x6e0 net/ipv6/mcast.c:1868
 mld_send_cr net/ipv6/mcast.c:2169 [inline]
 mld_ifc_work+0x55c/0x840 net/ipv6/mcast.c:2702
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3321
 worker_thread+0x582/0x770 kernel/workqueue.c:3402
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0xffff88810bfc2000 -> 0xffff88810165d000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4085 Comm: kworker/0:6 Not tainted 6.15.0-syzkaller-13473-gc0c9379f235d #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: mld mld_ifc_work
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