==================================================================
BUG: KASAN: use-after-free in ip6_dst_idev include/net/ip6_fib.h:141 [inline]
BUG: KASAN: use-after-free in ip6_xmit+0x177c/0x1a00 net/ipv6/ip6_output.c:237
Read of size 8 at addr ffff8801d8bad8d8 by task syz-executor1/21104

CPU: 1 PID: 21104 Comm: syz-executor1 Not tainted 4.4.147-ga5fc665 #80
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 218867d961a87f09 ffff8800b6d9f5c8 ffffffff81e12a4d
 ffffea000762eb40 ffff8801d8bad8d8 0000000000000000 ffff8801d8bad8d8
 0000000000001200 ffff8800b6d9f600 ffffffff81517fd6 ffff8801d8bad8d8
Call Trace:
 [<ffffffff81e12a4d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e12a4d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81517fd6>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff815182f5>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff815182f5>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814fbde4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff8343276c>] ip6_dst_idev include/net/ip6_fib.h:141 [inline]
 [<ffffffff8343276c>] ip6_xmit+0x177c/0x1a00 net/ipv6/ip6_output.c:237
 [<ffffffff834f27b5>] inet6_csk_xmit+0x245/0x490 net/ipv6/inet6_connection_sock.c:176
 [<ffffffff835a1dfb>] l2tp_xmit_core net/l2tp/l2tp_core.c:1084 [inline]
 [<ffffffff835a1dfb>] l2tp_xmit_skb+0xbeb/0xeb0 net/l2tp/l2tp_core.c:1179
 [<ffffffff835ae330>] pppol2tp_sendmsg+0x4e0/0x7d0 net/l2tp/l2tp_ppp.c:355
 [<ffffffff82f2391c>] sock_sendmsg_nosec net/socket.c:626 [inline]
 [<ffffffff82f2391c>] sock_sendmsg+0xcc/0x110 net/socket.c:636
 [<ffffffff82f250e1>] ___sys_sendmsg+0x441/0x880 net/socket.c:1963
 [<ffffffff82f276be>] __sys_sendmmsg+0x12e/0x2e0 net/socket.c:2048
 [<ffffffff82f278a5>] SYSC_sendmmsg net/socket.c:2078 [inline]
 [<ffffffff82f278a5>] SyS_sendmmsg+0x35/0x60 net/socket.c:2073
 [<ffffffff838c8c65>] entry_SYSCALL_64_fastpath+0x22/0x9e

Allocated by task 19025:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fae93>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fb177>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fb177>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814fb742>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff814f723e>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff814f723e>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff814f723e>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff814f723e>] kmem_cache_alloc+0xbe/0x2a0 mm/slub.c:2628
 [<ffffffff82fa1e85>] dst_alloc+0xb5/0x1a0 net/core/dst.c:210
 [<ffffffff831ef018>] rt_dst_alloc+0x78/0x430 net/ipv4/route.c:1478
 [<ffffffff831f84dc>] __mkroute_output net/ipv4/route.c:2132 [inline]
 [<ffffffff831f84dc>] __ip_route_output_key_hash+0x9ac/0x2380 net/ipv4/route.c:2344
 [<ffffffff831fa989>] __ip_route_output_key include/net/route.h:124 [inline]
 [<ffffffff831fa989>] ip_route_output_flow+0x29/0xa0 net/ipv4/route.c:2431
 [<ffffffff83225f15>] ip_route_output_key include/net/route.h:134 [inline]
 [<ffffffff83225f15>] ip_send_unicast_reply+0x515/0xd20 net/ipv4/ip_output.c:1592
 [<ffffffff832a6054>] tcp_v4_send_reset+0x954/0x1740 net/ipv4/tcp_ipv4.c:695
 [<ffffffff832ab7aa>] tcp_v4_rcv+0xd4a/0x30b0 net/ipv4/tcp_ipv4.c:1704
 [<ffffffff83206d37>] ip_local_deliver_finish+0x257/0xa60 net/ipv4/ip_input.c:216
 [<ffffffff832092b1>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
 [<ffffffff832092b1>] NF_HOOK include/linux/netfilter.h:249 [inline]
 [<ffffffff832092b1>] ip_local_deliver+0x1f1/0x380 net/ipv4/ip_input.c:257
 [<ffffffff83207b9a>] dst_input include/net/dst.h:504 [inline]
 [<ffffffff83207b9a>] ip_rcv_finish+0x65a/0x1640 net/ipv4/ip_input.c:365
 [<ffffffff83209e24>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
 [<ffffffff83209e24>] NF_HOOK include/linux/netfilter.h:249 [inline]
 [<ffffffff83209e24>] ip_rcv+0x9e4/0x1190 net/ipv4/ip_input.c:455
 [<ffffffff82f84176>] __netif_receive_skb_core+0x12d6/0x2940 net/core/dev.c:4019
 [<ffffffff82f8583b>] __netif_receive_skb+0x5b/0x1c0 net/core/dev.c:4054
 [<ffffffff82f89d56>] process_backlog+0x216/0x6a0 net/core/dev.c:4647
 [<ffffffff82f86c12>] napi_poll net/core/dev.c:4885 [inline]
 [<ffffffff82f86c12>] net_rx_action+0x3a2/0xdb0 net/core/dev.c:4950
 [<ffffffff838cc17c>] __do_softirq+0x22c/0xa1a kernel/softirq.c:273

Freed by task 20650:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fae93>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fb7c2>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fb7c2>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f894e>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f894e>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f894e>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f894e>] kmem_cache_free+0xbe/0x340 mm/slub.c:2881
 [<ffffffff82fa1135>] dst_destroy.part.6+0x1f5/0x330 net/core/dst.c:270
 [<ffffffff82fa1285>] dst_destroy+0x15/0x20 net/core/dst.c:252
 [<ffffffff831f20cc>] dst_free include/net/dst.h:425 [inline]
 [<ffffffff831f20cc>] dst_rcu_free+0x9c/0xc0 include/net/dst.h:435
 [<ffffffff81287fc7>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff81287fc7>] rcu_do_batch kernel/rcu/tree.c:2705 [inline]
 [<ffffffff81287fc7>] invoke_rcu_callbacks kernel/rcu/tree.c:2973 [inline]
 [<ffffffff81287fc7>] __rcu_process_callbacks kernel/rcu/tree.c:2940 [inline]
 [<ffffffff81287fc7>] rcu_process_callbacks+0x927/0x1440 kernel/rcu/tree.c:2957
 [<ffffffff838cc17c>] __do_softirq+0x22c/0xa1a kernel/softirq.c:273

The buggy address belongs to the object at ffff8801d8bad8c0
 which belongs to the cache ip_dst_cache of size 208
The buggy address is located 24 bytes inside of
 208-byte region [ffff8801d8bad8c0, ffff8801d8bad990)
The buggy address belongs to the page:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access[  332.717130] ------------[ cut here ]------------
WARNING: CPU: 0 PID: 3830 at kernel/sched/core.c:7946 __might_sleep+0x138/0x1a0 kernel/sched/core.c:7941()
do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff8113c9de>] do_wait+0x26e/0xa30 kernel/exit.c:1503