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BUG: KMSAN: use-after-free in l3mdev_master_ifindex_rcu+0x104/0x200 net/l3mdev/l3mdev.c:24
CPU: 1 PID: 17299 Comm: syz-executor.1 Not tainted 5.6.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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
 sctp_v6_get_dst+0x9ee/0x1e90 net/sctp/ipv6.c:278
 sctp_transport_route+0x213/0xc10 net/sctp/transport.c:297
 sctp_assoc_add_peer+0xb72/0x20d0 net/sctp/associola.c:659
 sctp_connect_new_asoc+0x690/0xc10 net/sctp/socket.c:1077
 __sctp_connect+0xb68/0x1ef0 net/sctp/socket.c:1175
 __sctp_setsockopt_connectx net/sctp/socket.c:1321 [inline]
 sctp_getsockopt_connectx3 net/sctp/socket.c:1406 [inline]
 sctp_getsockopt+0xf2da/0x19af0 net/sctp/socket.c:8077
 sock_common_getsockopt+0x13f/0x180 net/core/sock.c:3108
 __sys_getsockopt+0x533/0x7b0 net/socket.c:2175
 __do_sys_getsockopt net/socket.c:2190 [inline]
 __se_sys_getsockopt+0xe1/0x100 net/socket.c:2187
 __x64_sys_getsockopt+0x62/0x80 net/socket.c:2187
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c849
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f013826bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007f013826c6d4 RCX: 000000000045c849
RDX: 000000000000006f RSI: 0000000000000084 RDI: 0000000000000004
RBP: 000000000076bf00 R08: 0000000020000180 R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000001a3 R14: 00000000004d2578 R15: 000000000076bf0c

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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