syzbot

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BUG: KMSAN: use-after-free in l3mdev_master_ifindex_rcu+0x104/0x200 net/l3mdev/l3mdev.c:24
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.6.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 l3mdev_master_ifindex_rcu+0x104/0x200 net/l3mdev/l3mdev.c:24
 ipv6_dev_get_saddr+0x516/0xe10 net/ipv6/addrconf.c:1817
 ip6_route_get_saddr include/net/ip6_route.h:144 [inline]
 ip6_dst_lookup_tail+0x1dee/0x2010 net/ipv6/ip6_output.c:1030
 ip6_dst_lookup_flow+0x102/0x250 net/ipv6/ip6_output.c:1153
 geneve_get_v6_dst+0x7c2/0xa00 drivers/net/geneve.c:856
 geneve6_xmit_skb drivers/net/geneve.c:950 [inline]
 geneve_xmit+0x5d3/0x2c20 drivers/net/geneve.c:1001
 __netdev_start_xmit include/linux/netdevice.h:4524 [inline]
 netdev_start_xmit include/linux/netdevice.h:4538 [inline]
 xmit_one net/core/dev.c:3470 [inline]
 dev_hard_start_xmit+0x531/0xab0 net/core/dev.c:3486
 __dev_queue_xmit+0x37de/0x4220 net/core/dev.c:4063
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:4096
 neigh_resolve_output+0xab0/0xb40 net/core/neighbour.c:1487
 neigh_output include/net/neighbour.h:510 [inline]
 ip6_finish_output2+0x20fd/0x2640 net/ipv6/ip6_output.c:116
 __ip6_finish_output+0x824/0x8e0 net/ipv6/ip6_output.c:142
 ip6_finish_output+0x166/0x410 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x60a/0x770 net/ipv6/ip6_output.c:175
 dst_output include/net/dst.h:436 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ndisc_send_skb+0x1047/0x15a0 net/ipv6/ndisc.c:505
 ndisc_send_ns+0xe38/0xe80 net/ipv6/ndisc.c:647
 addrconf_dad_work+0xc0b/0x2aa0 net/ipv6/addrconf.c:4120
 process_one_work+0x1555/0x1f40 kernel/workqueue.c:2264
 worker_thread+0xef6/0x2450 kernel/workqueue.c:2410
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:353

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_free+0x6e/0xb0 mm/kmsan/kmsan_hooks.c:107
 slab_free_freelist_hook mm/slub.c:1477 [inline]
 slab_free mm/slub.c:3040 [inline]
 kfree+0x565/0x30a0 mm/slub.c:3993
 __netdev_name_node_alt_destroy net/core/dev.c:322 [inline]
 netdev_name_node_alt_destroy+0x587/0x690 net/core/dev.c:334
 rtnl_alt_ifname net/core/rtnetlink.c:3518 [inline]
 rtnl_linkprop+0x939/0xc00 net/core/rtnetlink.c:3567
 rtnl_dellinkprop+0x9d/0xb0 net/core/rtnetlink.c:3588
 rtnetlink_rcv_msg+0x1153/0x1570 net/core/rtnetlink.c:5438
 netlink_rcv_skb+0x451/0x650 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:5456
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2343
 ___sys_sendmsg net/socket.c:2397 [inline]
 __sys_sendmsg+0x451/0x5f0 net/socket.c:2430
 __do_sys_sendmsg net/socket.c:2439 [inline]
 __se_sys_sendmsg+0x97/0xb0 net/socket.c:2437
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2437
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
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