syzbot

IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
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BUG: KCSAN: data-race in __ipv6_dev_get_saddr / addrconf_dad_work

read to 0xffff888098c45c2c of 4 bytes by interrupt on cpu 1:
 __ipv6_dev_get_saddr+0xbc/0x2d0 net/ipv6/addrconf.c:1667
 ipv6_dev_get_saddr+0x564/0x5f0 net/ipv6/addrconf.c:1822
 ip6_route_get_saddr include/net/ip6_route.h:144 [inline]
 ip6_dst_lookup_tail+0x98e/0xc50 net/ipv6/ip6_output.c:1030
 ip6_dst_lookup_flow+0x5c/0x110 net/ipv6/ip6_output.c:1153
 geneve_get_v6_dst+0x22e/0x440 drivers/net/geneve.c:856
 geneve6_xmit_skb drivers/net/geneve.c:950 [inline]
 geneve_xmit+0x1d6/0x1538 drivers/net/geneve.c:1001
 __netdev_start_xmit include/linux/netdevice.h:4447 [inline]
 netdev_start_xmit include/linux/netdevice.h:4461 [inline]
 xmit_one net/core/dev.c:3420 [inline]
 dev_hard_start_xmit+0xef/0x430 net/core/dev.c:3436
 __dev_queue_xmit+0x14e9/0x1ba0 net/core/dev.c:4013
 dev_queue_xmit+0x21/0x30 net/core/dev.c:4046
 neigh_hh_output include/net/neighbour.h:500 [inline]
 neigh_output include/net/neighbour.h:509 [inline]
 ip6_finish_output2+0x7e8/0xf60 net/ipv6/ip6_output.c:116
 __ip6_finish_output net/ipv6/ip6_output.c:142 [inline]
 __ip6_finish_output+0x2d7/0x330 net/ipv6/ip6_output.c:127
 ip6_finish_output+0x41/0x160 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x108/0x290 net/ipv6/ip6_output.c:175
 dst_output include/net/dst.h:436 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 mld_sendpack+0x53c/0x5b0 net/ipv6/mcast.c:1682
 mld_send_initial_cr.part.0+0xd7/0x100 net/ipv6/mcast.c:2099
 mld_send_initial_cr net/ipv6/mcast.c:2083 [inline]
 mld_dad_timer_expire+0x4b/0x190 net/ipv6/mcast.c:2118
 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers kernel/time/timer.c:1773 [inline]
 __run_timers kernel/time/timer.c:1740 [inline]
 run_timer_softirq+0xc0c/0xcd0 kernel/time/timer.c:1786
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
 smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffff888098c45c2c of 4 bytes by task 3606 on cpu 0:
 addrconf_dad_work+0x4ef/0xba0 net/ipv6/addrconf.c:4103
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3606 Comm: kworker/0:2 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_dad_work
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