==================================================================
BUG: KASAN: slab-out-of-bounds in __ipv6_addr_type+0x26c/0x290 net/ipv6/addrconf_core.c:68
Read of size 4 at addr ffff8800a4fefd38 by task syz-executor.2/2534

CPU: 0 PID: 2534 Comm: syz-executor.2 Not tainted 4.4.174+ #4
 0000000000000000 c748c075853837b1 ffff8800a6b66da0 ffffffff81aad1a1
 0000000000000000 ffffea000293fb00 ffff8800a4fefd38 0000000000000004
 ffff8800a4fefa80 ffff8800a6b66dd8 ffffffff81490120 0000000000000000
Call Trace:
 [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81490120>] print_address_description+0x6f/0x21b mm/kasan/report.c:252
 [<ffffffff81490358>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81490358>] kasan_report mm/kasan/report.c:408 [inline]
 [<ffffffff81490358>] kasan_report.cold+0x8c/0x2be mm/kasan/report.c:393
 [<ffffffff81484eb4>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff826bbd4c>] __ipv6_addr_type+0x26c/0x290 net/ipv6/addrconf_core.c:68
 [<ffffffff826b141c>] ipv6_addr_type include/net/ipv6.h:330 [inline]
 [<ffffffff826b141c>] ip6_tnl_xmit2+0x2ac/0x2320 net/ipv6/ip6_tunnel.c:988
 [<ffffffff826b4e59>] ip4ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1134 [inline]
 [<ffffffff826b4e59>] ip6_tnl_xmit+0xa09/0xe00 net/ipv6/ip6_tunnel.c:1212
 [<ffffffff82245071>] __netdev_start_xmit include/linux/netdevice.h:3750 [inline]
 [<ffffffff82245071>] netdev_start_xmit include/linux/netdevice.h:3759 [inline]
 [<ffffffff82245071>] xmit_one net/core/dev.c:2781 [inline]
 [<ffffffff82245071>] dev_hard_start_xmit+0x7c1/0x11e0 net/core/dev.c:2797
 [<ffffffff822473cb>] __dev_queue_xmit+0x164b/0x1bb0 net/core/dev.c:3229
 [<ffffffff82247948>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3263
 [<ffffffff8225c136>] neigh_direct_output+0x16/0x20 net/core/neighbour.c:1369
 [<ffffffff823c5412>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff823c5412>] ip_finish_output2+0x6a2/0x1280 net/ipv4/ip_output.c:213
 [<ffffffff823cc6e2>] ip_finish_output+0x8b2/0xc60 net/ipv4/ip_output.c:288
 [<ffffffff823d04a7>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff823d04a7>] ip_output+0x227/0x4c0 net/ipv4/ip_output.c:362
 [<ffffffff823cd21c>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff823cd21c>] ip_local_out+0x9c/0x180 net/ipv4/ip_output.c:119
 [<ffffffff823d300e>] ip_send_skb+0x3e/0xc0 net/ipv4/ip_output.c:1453
 [<ffffffff82478ded>] udp_send_skb+0x4fd/0xc70 net/ipv4/udp.c:842
 [<ffffffff8247fb9f>] udp_sendmsg+0x16cf/0x1c60 net/ipv4/udp.c:1072
 [<ffffffff826137a2>] udpv6_sendmsg+0x12f2/0x24f0 net/ipv6/udp.c:1173
 [<ffffffff824a8b42>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
 [<ffffffff821da269>] ___sys_sendmsg+0x769/0x890 net/socket.c:1975
 [<ffffffff821dd0c5>] __sys_sendmsg+0xc5/0x160 net/socket.c:2009
 [<ffffffff821dd18d>] SYSC_sendmsg net/socket.c:2020 [inline]
 [<ffffffff821dd18d>] SyS_sendmsg+0x2d/0x50 net/socket.c:2016
 [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

Allocated by task 2534:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81483f22>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81483f22>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81483f22>] kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:616
 [<ffffffff81484197>] kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:601
 [<ffffffff81480521>] __kmalloc+0x141/0x330 mm/slub.c:3613
 [<ffffffff82264216>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff82264216>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff82264216>] neigh_alloc net/core/neighbour.c:285 [inline]
 [<ffffffff82264216>] __neigh_create+0x1d6/0x1b30 net/core/neighbour.c:457
 [<ffffffff823a024e>] neigh_create include/net/neighbour.h:313 [inline]
 [<ffffffff823a024e>] ipv4_neigh_lookup+0x52e/0x6e0 net/ipv4/route.c:464
 [<ffffffff826b13eb>] dst_neigh_lookup include/net/dst.h:466 [inline]
 [<ffffffff826b13eb>] ip6_tnl_xmit2+0x27b/0x2320 net/ipv6/ip6_tunnel.c:982
 [<ffffffff826b4e59>] ip4ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1134 [inline]
 [<ffffffff826b4e59>] ip6_tnl_xmit+0xa09/0xe00 net/ipv6/ip6_tunnel.c:1212
 [<ffffffff82245071>] __netdev_start_xmit include/linux/netdevice.h:3750 [inline]
 [<ffffffff82245071>] netdev_start_xmit include/linux/netdevice.h:3759 [inline]
 [<ffffffff82245071>] xmit_one net/core/dev.c:2781 [inline]
 [<ffffffff82245071>] dev_hard_start_xmit+0x7c1/0x11e0 net/core/dev.c:2797
 [<ffffffff822473cb>] __dev_queue_xmit+0x164b/0x1bb0 net/core/dev.c:3229
 [<ffffffff82247948>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3263
 [<ffffffff8225c136>] neigh_direct_output+0x16/0x20 net/core/neighbour.c:1369
 [<ffffffff823c5412>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff823c5412>] ip_finish_output2+0x6a2/0x1280 net/ipv4/ip_output.c:213
 [<ffffffff823cc6e2>] ip_finish_output+0x8b2/0xc60 net/ipv4/ip_output.c:288
 [<ffffffff823d04a7>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff823d04a7>] ip_output+0x227/0x4c0 net/ipv4/ip_output.c:362
 [<ffffffff823cd21c>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff823cd21c>] ip_local_out+0x9c/0x180 net/ipv4/ip_output.c:119
 [<ffffffff823d300e>] ip_send_skb+0x3e/0xc0 net/ipv4/ip_output.c:1453
 [<ffffffff82478ded>] udp_send_skb+0x4fd/0xc70 net/ipv4/udp.c:842
 [<ffffffff8247fb9f>] udp_sendmsg+0x16cf/0x1c60 net/ipv4/udp.c:1072
 [<ffffffff826137a2>] udpv6_sendmsg+0x12f2/0x24f0 net/ipv6/udp.c:1173
 [<ffffffff824a8b42>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
 [<ffffffff821da269>] ___sys_sendmsg+0x769/0x890 net/socket.c:1975
 [<ffffffff821dd0c5>] __sys_sendmsg+0xc5/0x160 net/socket.c:2009
 [<ffffffff821dd18d>] SYSC_sendmsg net/socket.c:2020 [inline]
 [<ffffffff821dd18d>] SyS_sendmsg+0x2d/0x50 net/socket.c:2016
 [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

Freed by task 996:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81484820>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81484820>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81484820>] kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:589
 [<ffffffff81481c44>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff81481c44>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff81481c44>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff81481c44>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff821fd036>] skb_free_head net/core/skbuff.c:571 [inline]
 [<ffffffff821fd036>] skb_release_data+0x2e6/0x380 net/core/skbuff.c:602
 [<ffffffff821fd11d>] skb_release_all+0x4d/0x60 net/core/skbuff.c:661
 [<ffffffff821fd257>] __kfree_skb net/core/skbuff.c:675 [inline]
 [<ffffffff821fd257>] kfree_skb+0xf7/0x400 net/core/skbuff.c:696
 [<ffffffff826aa4ab>] ipip6_tunnel_xmit net/ipv6/sit.c:998 [inline]
 [<ffffffff826aa4ab>] sit_tunnel_xmit+0xfdb/0x2610 net/ipv6/sit.c:1030
 [<ffffffff82245071>] __netdev_start_xmit include/linux/netdevice.h:3750 [inline]
 [<ffffffff82245071>] netdev_start_xmit include/linux/netdevice.h:3759 [inline]
 [<ffffffff82245071>] xmit_one net/core/dev.c:2781 [inline]
 [<ffffffff82245071>] dev_hard_start_xmit+0x7c1/0x11e0 net/core/dev.c:2797
 [<ffffffff822473cb>] __dev_queue_xmit+0x164b/0x1bb0 net/core/dev.c:3229
 [<ffffffff82247948>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3263
 [<ffffffff8225c136>] neigh_direct_output+0x16/0x20 net/core/neighbour.c:1369
 [<ffffffff8259f877>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff8259f877>] ip6_finish_output2+0x9c7/0x1dc0 net/ipv6/ip6_output.c:113
 [<ffffffff825b0203>] ip6_finish_output+0x2f3/0x750 net/ipv6/ip6_output.c:131
 [<ffffffff825b0814>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff825b0814>] ip6_output+0x1b4/0x520 net/ipv6/ip6_output.c:145
 [<ffffffff826bf66c>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff826bf66c>] ip6_local_out+0x9c/0x180 net/ipv6/output_core.c:169
 [<ffffffff825b28c2>] ip6_send_skb+0xa2/0x340 net/ipv6/ip6_output.c:1725
 [<ffffffff82611a3c>] udp_v6_send_skb+0x85c/0xe90 net/ipv6/udp.c:1066
 [<ffffffff826142ed>] udpv6_sendmsg+0x1e3d/0x24f0 net/ipv6/udp.c:1330
 [<ffffffff824a8b42>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
 [<ffffffff821d9e69>] ___sys_sendmsg+0x369/0x890 net/socket.c:1975
 [<ffffffff821dd2e0>] __sys_sendmmsg+0x130/0x2e0 net/socket.c:2060
 [<ffffffff821dd4c5>] SYSC_sendmmsg net/socket.c:2090 [inline]
 [<ffffffff821dd4c5>] SyS_sendmmsg+0x35/0x60 net/socket.c:2085
 [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

The buggy address belongs to the object at ffff8800a4fefa80
 which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 696 bytes inside of
 1024-byte region [ffff8800a4fefa80, ffff8800a4fefe80)
The buggy address belongs to the page:
audit: type=1400 audit(1559652097.754:391): avc:  denied  { sigchld } for  pid=2138 comm="syz-executor.3" scontext=system_u:object_r:unlabeled_t:s0 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=process permissive=0
------------[ cut here ]------------
WARNING: CPU: 1 PID: 2138 at lib/list_debug.c:51 __list_del_entry_valid+0x11d/0x1a0 lib/list_debug.c:51()
list_del corruption. prev->next should be ffff8800a6b67f20, but was ff12c45be8c48949