==================================================================
BUG: KASAN: use-after-free in ip6_dst_idev include/net/ip6_fib.h:141 [inline]
BUG: KASAN: use-after-free in ip6_xmit+0x1776/0x1a00 net/ipv6/ip6_output.c:237
Read of size 8 at addr ffff8801d984e518 by task syz-executor3/20011

CPU: 1 PID: 20011 Comm: syz-executor3 Not tainted 4.4.141-gbda6b6e #70
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 4dd675cb6cce134e ffff8801bbebf5c8 ffffffff81e0e16d
 ffffea0007661380 ffff8801d984e518 0000000000000000 ffff8801d984e518
 0000000000001200 ffff8801bbebf600 ffffffff81515a76 ffff8801d984e518
Call Trace:
 [<ffffffff81e0e16d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0e16d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81515a76>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff81515d95>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81515d95>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9884>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff8342ca86>] ip6_dst_idev include/net/ip6_fib.h:141 [inline]
 [<ffffffff8342ca86>] ip6_xmit+0x1776/0x1a00 net/ipv6/ip6_output.c:237
 [<ffffffff834ec905>] inet6_csk_xmit+0x245/0x490 net/ipv6/inet6_connection_sock.c:176
 [<ffffffff8359bdfb>] l2tp_xmit_core net/l2tp/l2tp_core.c:1084 [inline]
 [<ffffffff8359bdfb>] l2tp_xmit_skb+0xbeb/0xeb0 net/l2tp/l2tp_core.c:1179
 [<ffffffff835a8330>] pppol2tp_sendmsg+0x4e0/0x7d0 net/l2tp/l2tp_ppp.c:355
 [<ffffffff82f1e2dc>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82f1e2dc>] sock_sendmsg+0xcc/0x110 net/socket.c:635
 [<ffffffff82f1faa1>] ___sys_sendmsg+0x441/0x880 net/socket.c:1962
 [<ffffffff82f2207e>] __sys_sendmmsg+0x12e/0x2e0 net/socket.c:2047
 [<ffffffff82f22265>] SYSC_sendmmsg net/socket.c:2077 [inline]
 [<ffffffff82f22265>] SyS_sendmmsg+0x35/0x60 net/socket.c:2072
 [<ffffffff838c2be5>] entry_SYSCALL_64_fastpath+0x22/0x9e

Allocated by task 18627:
 [<ffffffff81033c86>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8933>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8c17>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8c17>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f91e2>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff814f4cde>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff814f4cde>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff814f4cde>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff814f4cde>] kmem_cache_alloc+0xbe/0x2a0 mm/slub.c:2628
 [<ffffffff82f9c925>] dst_alloc+0xb5/0x1a0 net/core/dst.c:210
 [<ffffffff831e9a68>] rt_dst_alloc+0x78/0x430 net/ipv4/route.c:1478
 [<ffffffff831f2f2c>] __mkroute_output net/ipv4/route.c:2132 [inline]
 [<ffffffff831f2f2c>] __ip_route_output_key_hash+0x9ac/0x2380 net/ipv4/route.c:2344
 [<ffffffff831f53d9>] __ip_route_output_key include/net/route.h:124 [inline]
 [<ffffffff831f53d9>] ip_route_output_flow+0x29/0xa0 net/ipv4/route.c:2431
 [<ffffffff832d1290>] udp_sendmsg+0x1480/0x1c70 net/ipv4/udp.c:1040
 [<ffffffff8349675d>] udpv6_sendmsg+0x12cd/0x24c0 net/ipv6/udp.c:1173
 [<ffffffff833010f3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f1e2dc>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82f1e2dc>] sock_sendmsg+0xcc/0x110 net/socket.c:635
 [<ffffffff82f1efbc>] SYSC_sendto+0x21c/0x370 net/socket.c:1665
 [<ffffffff82f21640>] SyS_sendto+0x40/0x50 net/socket.c:1633
 [<ffffffff838c2be5>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 18588:
 [<ffffffff81033c86>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8933>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f9262>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f9262>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f63ee>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f63ee>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f63ee>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f63ee>] kmem_cache_free+0xbe/0x340 mm/slub.c:2881
 [<ffffffff82f9bbd5>] dst_destroy.part.6+0x1f5/0x330 net/core/dst.c:270
 [<ffffffff82f9c255>] dst_destroy net/core/dst.c:252 [inline]
 [<ffffffff82f9c255>] dst_destroy_rcu+0x15/0x40 net/core/dst.c:295
 [<ffffffff81285d57>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff81285d57>] rcu_do_batch kernel/rcu/tree.c:2705 [inline]
 [<ffffffff81285d57>] invoke_rcu_callbacks kernel/rcu/tree.c:2973 [inline]
 [<ffffffff81285d57>] __rcu_process_callbacks kernel/rcu/tree.c:2940 [inline]
 [<ffffffff81285d57>] rcu_process_callbacks+0x927/0x1440 kernel/rcu/tree.c:2957
 [<ffffffff838c60ac>] __do_softirq+0x22c/0xa1a kernel/softirq.c:273

The buggy address belongs to the object at ffff8801d984e500
 which belongs to the cache ip_dst_cache of size 208
The buggy address is located 24 bytes inside of
 208-byte region [ffff8801d984e500, ffff8801d984e5d0)
The buggy address belongs to the page:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 19995 at lib/list_debug.c:29 __list_add+0x120/0x1c0 lib/list_debug.c:26()
list_add corruption. next->prev should be prev (ffff8801db21fe70), but was ffffffff83aaa220. (next=ffff8801bb5ce088).