==================================================================
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 ffff8800a3c07518 by task syz-executor1/24267

CPU: 0 PID: 24267 Comm: syz-executor1 Not tainted 4.4.153-g5e24b4e #90
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 e32b41490bb92e4f ffff8801ba57f5c8 ffffffff81e162ed
 ffffea00028f01c0 ffff8800a3c07518 0000000000000000 ffff8800a3c07518
 0000000000001000 ffff8801ba57f600 ffffffff8151b4d9 ffff8800a3c07518
Call Trace:
 [<ffffffff81e162ed>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e162ed>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8151b4d9>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff8151b7f8>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8151b7f8>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814fe784>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff834361fc>] ip6_dst_idev include/net/ip6_fib.h:141 [inline]
 [<ffffffff834361fc>] ip6_xmit+0x177c/0x1a00 net/ipv6/ip6_output.c:237
 [<ffffffff834f63c5>] inet6_csk_xmit+0x245/0x490 net/ipv6/inet6_connection_sock.c:176
 [<ffffffff835a5a0c>] l2tp_xmit_core net/l2tp/l2tp_core.c:1084 [inline]
 [<ffffffff835a5a0c>] l2tp_xmit_skb+0xb9c/0xe80 net/l2tp/l2tp_core.c:1179
 [<ffffffff835b1f60>] pppol2tp_sendmsg+0x4e0/0x7d0 net/l2tp/l2tp_ppp.c:355
 [<ffffffff82f2757c>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff82f2757c>] sock_sendmsg+0xcc/0x110 net/socket.c:648
 [<ffffffff82f28d41>] ___sys_sendmsg+0x441/0x880 net/socket.c:1975
 [<ffffffff82f2b32e>] __sys_sendmmsg+0x12e/0x2e0 net/socket.c:2060
 [<ffffffff82f2b515>] SYSC_sendmmsg net/socket.c:2090 [inline]
 [<ffffffff82f2b515>] SyS_sendmmsg+0x35/0x60 net/socket.c:2085
 [<ffffffff838cc865>] entry_SYSCALL_64_fastpath+0x22/0x9e

Allocated by task 21853:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fd823>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fdb07>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fdb07>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814fe0d2>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff814f9bee>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff814f9bee>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff814f9bee>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff814f9bee>] kmem_cache_alloc+0xbe/0x2a0 mm/slub.c:2628
 [<ffffffff82fa5b35>] dst_alloc+0xb5/0x1a0 net/core/dst.c:210
 [<ffffffff831f2cc8>] rt_dst_alloc+0x78/0x430 net/ipv4/route.c:1478
 [<ffffffff831fc18c>] __mkroute_output net/ipv4/route.c:2132 [inline]
 [<ffffffff831fc18c>] __ip_route_output_key_hash+0x9ac/0x2380 net/ipv4/route.c:2344
 [<ffffffff831fe639>] __ip_route_output_key include/net/route.h:124 [inline]
 [<ffffffff831fe639>] ip_route_output_flow+0x29/0xa0 net/ipv4/route.c:2431
 [<ffffffff832c8243>] ip_route_connect include/net/route.h:304 [inline]
 [<ffffffff832c8243>] __ip4_datagram_connect+0x663/0xfe0 net/ipv4/datagram.c:51
 [<ffffffff832c8bef>] ip4_datagram_connect+0x2f/0x50 net/ipv4/datagram.c:92
 [<ffffffff83303357>] inet_dgram_connect+0x117/0x200 net/ipv4/af_inet.c:550
 [<ffffffff82f27ef8>] SYSC_connect+0x1b8/0x300 net/socket.c:1570
 [<ffffffff82f2a844>] SyS_connect+0x24/0x30 net/socket.c:1551
 [<ffffffff838cc865>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 19699:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fd823>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fe152>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fe152>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814fb33e>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814fb33e>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814fb33e>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814fb33e>] kmem_cache_free+0xbe/0x340 mm/slub.c:2881
 [<ffffffff82fa4de5>] dst_destroy.part.6+0x1f5/0x330 net/core/dst.c:270
 [<ffffffff82fa5465>] dst_destroy net/core/dst.c:252 [inline]
 [<ffffffff82fa5465>] dst_destroy_rcu+0x15/0x40 net/core/dst.c:295
 [<ffffffff81288d97>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff81288d97>] rcu_do_batch kernel/rcu/tree.c:2705 [inline]
 [<ffffffff81288d97>] invoke_rcu_callbacks kernel/rcu/tree.c:2973 [inline]
 [<ffffffff81288d97>] __rcu_process_callbacks kernel/rcu/tree.c:2940 [inline]
 [<ffffffff81288d97>] rcu_process_callbacks+0x927/0x1440 kernel/rcu/tree.c:2957
 [<ffffffff838cfd7c>] __do_softirq+0x22c/0xa1a kernel/softirq.c:273

The buggy address belongs to the object at ffff8800a3c07500
 which belongs to the cache ip_dst_cache of size 208
The buggy address is located 24 bytes inside of
 208-byte region [ffff8800a3c07500, ffff8800a3c075d0)
The buggy address belongs to the page:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 24283 Comm: syz-executor5 Not tainted 4.4.153-g5e24b4e #90
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800a1504800 task.stack: ffff8801bbcb0000
RIP: 0010:[<ffffffff832c4073>]  [<ffffffff832c4073>] tcp_rack_mark_lost+0x2f3/0x6f0 net/ipv4/tcp_recovery.c:53
RSP: 0018:ffff8801db307450  EFLAGS: 00010203
RAX: 0800000000000015 RBX: 000000000000008c RCX: 0000000000000005
RDX: 0000000000000100 RSI: ffffffff832c4067 RDI: 40000000000000ac
RBP: ffff8801db3074d0 R08: 000000000000452e R09: 0000000000000014
R10: ffffed0043fffa09 R11: 0000000000000008 R12: 4000000000000080
R13: 000000007d73c8a0 R14: dffffc0000000000 R15: ffff8801d271c980
FS:  00007fa745249700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc1ed817fc0 CR3: 00000000b741a000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d271d0d8 00000008844bec20 ffff8801d271d1d4 1ffff1003a4e3a31
 ffff8801d271d188 ffffea00028f01f5 0003362a000003e8 000000008f68f1f8
 ffff8801d271cd68 ffffed003a4e3a1b ffff8801d271cb70 ffff8801d271c980
Call Trace:
 <IRQ> 
 [<ffffffff83271c55>] tcp_fastretrans_alert+0x1435/0x29a0 net/ipv4/tcp_input.c:2823
 [<ffffffff83274c97>] tcp_ack+0x1ad7/0x4760 net/ipv4/tcp_input.c:3648
 [<ffffffff8327a7d8>] tcp_rcv_established+0x3a8/0x1fe0 net/ipv4/tcp_input.c:5438
 [<ffffffff832ab0b5>] tcp_v4_do_rcv+0x5c5/0x990 net/ipv4/tcp_ipv4.c:1397
 [<ffffffff832b0ae3>] tcp_v4_rcv+0x23d3/0x30b0 net/ipv4/tcp_ipv4.c:1680
 [<ffffffff8320a9e7>] ip_local_deliver_finish+0x257/0xa60 net/ipv4/ip_input.c:216
 [<ffffffff8320cf61>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
 [<ffffffff8320cf61>] NF_HOOK include/linux/netfilter.h:249 [inline]
 [<ffffffff8320cf61>] ip_local_deliver+0x1f1/0x380 net/ipv4/ip_input.c:257
 [<ffffffff8320b84a>] dst_input include/net/dst.h:504 [inline]
 [<ffffffff8320b84a>] ip_rcv_finish+0x65a/0x1640 net/ipv4/ip_input.c:365
 [<ffffffff8320dad4>] NF_HOOK_THRESH include/linux/netfilter.h:226 [inline]
 [<ffffffff8320dad4>] NF_HOOK include/linux/netfilter.h:249 [inline]
 [<ffffffff8320dad4>] ip_rcv+0x9e4/0x1190 net/ipv4/ip_input.c:455
 [<ffffffff82f87e26>] __netif_receive_skb_core+0x12d6/0x2940 net/core/dev.c:4019
 [<ffffffff82f894eb>] __netif_receive_skb+0x5b/0x1c0 net/core/dev.c:4054
 [<ffffffff82f8da06>] process_backlog+0x216/0x6a0 net/core/dev.c:4647
 [<ffffffff82f8a8c2>] napi_poll net/core/dev.c:4885 [inline]
 [<ffffffff82f8a8c2>] net_rx_action+0x3a2/0xdb0 net/core/dev.c:4950
 [<ffffffff838cfd7c>] __do_softirq+0x22c/0xa1a kernel/softirq.c:273
 [<ffffffff838cdadc>] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:929
 <EOI> 
 [<ffffffff81140a44>] do_softirq.part.16+0x54/0x60 kernel/softirq.c:317
 [<ffffffff81140b16>] do_softirq arch/x86/include/asm/preempt.h:22 [inline]
 [<ffffffff81140b16>] __local_bh_enable_ip+0xc6/0xd0 kernel/softirq.c:170
 [<ffffffff838cbd70>] __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:178 [inline]
 [<ffffffff838cbd70>] _raw_spin_unlock_bh+0x30/0x40 kernel/locking/spinlock.c:207
 [<ffffffff82f34cb6>] spin_unlock_bh include/linux/spinlock.h:352 [inline]
 [<ffffffff82f34cb6>] release_sock+0x3b6/0x500 net/core/sock.c:2484
 [<ffffffff82f34f24>] sk_wait_data+0x124/0x3a0 net/core/sock.c:2064
 [<ffffffff832492cb>] tcp_recvmsg+0x19db/0x2df0 net/ipv4/tcp.c:1777
 [<ffffffff8330a4ae>] inet_recvmsg+0x23e/0x4c0 net/ipv4/af_inet.c:786
 [<ffffffff82f263a1>] sock_recvmsg_nosec net/socket.c:740 [inline]
 [<ffffffff82f263a1>] sock_recvmsg+0x91/0xc0 net/socket.c:748
 [<ffffffff82f293e5>] ___sys_recvmsg+0x265/0x590 net/socket.c:2129
 [<ffffffff82f2b616>] __sys_recvmsg+0xd6/0x190 net/socket.c:2175
 [<ffffffff82f2b6fd>] SYSC_recvmsg net/socket.c:2187 [inline]
 [<ffffffff82f2b6fd>] SyS_recvmsg+0x2d/0x50 net/socket.c:2182
 [<ffffffff838cc865>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: e8 03 42 80 3c 30 00 0f 85 48 03 00 00 4d 39 a7 e8 03 00 00 0f 84 b7 02 00 00 e8 29 05 09 fe 49 8d 7c 24 2c 48 89 f8 48 c1 e8 03 <42> 0f b6 14 30 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 
RIP  [<ffffffff832c4073>] tcp_rack_mark_lost+0x2f3/0x6f0 net/ipv4/tcp_recovery.c:53
 RSP <ffff8801db307450>
------------[ cut here ]------------
WARNING: CPU: 1 PID: 24283 at lib/list_debug.c:29 __list_add+0x120/0x1c0 lib/list_debug.c:26()
list_add corruption. next->prev should be prev (ffff8801db21fef0), but was ffffffff83aaae60. (next=ffff8801b9d41888).