==================================================================
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 ffff8800b993fb58 by task syz-executor4/26623

CPU: 1 PID: 26623 Comm: syz-executor4 Not tainted 4.4.147-ga5fc665 #80
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 41cada7cbc742bdc ffff8800a2e67618 ffffffff81e12a4d
 ffffea0002e64fc0 ffff8800b993fb58 0000000000000000 ffff8800b993fb58
 000000000000cd00 ffff8800a2e67650 ffffffff81517fd6 ffff8800b993fb58
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
 [<ffffffff82f23b83>] sock_write_iter+0x223/0x3b0 net/socket.c:835
 [<ffffffff8151febc>] do_iter_readv_writev+0x13c/0x1e0 fs/read_write.c:664
 [<ffffffff815215e0>] do_readv_writev+0x2e0/0x6e0 fs/read_write.c:808
 [<ffffffff81521b0b>] vfs_writev+0x7b/0xb0 fs/read_write.c:847
 [<ffffffff81523fd9>] SYSC_writev fs/read_write.c:880 [inline]
 [<ffffffff81523fd9>] SyS_writev+0xd9/0x250 fs/read_write.c:872
 [<ffffffff838c8c65>] entry_SYSCALL_64_fastpath+0x22/0x9e

Allocated by task 26570:
 [<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
 [<ffffffff832d6e10>] udp_sendmsg+0x1480/0x1c70 net/ipv4/udp.c:1040
 [<ffffffff83306c83>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f2391c>] sock_sendmsg_nosec net/socket.c:626 [inline]
 [<ffffffff82f2391c>] sock_sendmsg+0xcc/0x110 net/socket.c:636
 [<ffffffff82f253e5>] ___sys_sendmsg+0x745/0x880 net/socket.c:1963
 [<ffffffff82f27486>] __sys_sendmsg+0xd6/0x190 net/socket.c:1997
 [<ffffffff82f2756d>] SYSC_sendmsg net/socket.c:2008 [inline]
 [<ffffffff82f2756d>] SyS_sendmsg+0x2d/0x50 net/socket.c:2004
 [<ffffffff838c8c65>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 14:
 [<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
 [<ffffffff82fa17b5>] dst_destroy net/core/dst.c:252 [inline]
 [<ffffffff82fa17b5>] dst_destroy_rcu+0x15/0x40 net/core/dst.c:295
 [<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 ffff8800b993fb40
 which belongs to the cache ip_dst_cache of size 208
The buggy address is located 24 bytes inside of
 208-byte region [ffff8800b993fb40, ffff8800b993fc10)
The buggy address belongs to the page:
BUG: unable to handle kernel paging request at fffffbfff37a7c80
IP: [<ffffffff81226f3c>] cpuacct_charge+0x14c/0x380 kernel/sched/cpuacct.c:247
PGD 21ff67067 PUD 21ff66067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 26595 Comm: syz-executor7 Not tainted 4.4.147-ga5fc665 #80
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801b8c23000 task.stack: ffff8801b8e38000
RIP: 0010:[<ffffffff81226f3c>]  [<ffffffff81226f3c>] cpuacct_charge+0x14c/0x380 kernel/sched/cpuacct.c:247
RSP: 0018:ffff8801b8e3f890  EFLAGS: 00010046
RAX: 1ffffffff089521f RBX: 00000000000185a8 RCX: ffffffff84a16600
RDX: fffffbfff37a7c80 RSI: ffffffff9bd3e400 RDI: ffffffff844a90f8
RBP: ffff8801b8e3f8d0 R08: ffff8801b8c23950 R09: 0000000000000001
R10: 0000000000000001 R11: ffff8801b8c23000 R12: ffffffff844a9020
R13: dffffc0000000000 R14: 000000001d98ee3a R15: 0000000002e64fc0
FS:  0000000001ef7940(0063) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff37a7c80 CR3: 00000001c7b72000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81226e50 0000000000000046 0000000000000003 ffff8801d7d11860
 ffff8801d7d11800 000000001d98ee3a ffff8801d7d118b0 0000000000000000
 ffff8801b8e3f918 ffffffff811db4c9 0000000000000005 ffff8801db31f558
Call Trace:
 [<ffffffff811db4c9>] update_curr+0x2c9/0x6d0 kernel/sched/fair.c:882
 [<ffffffff811e66ca>] enqueue_entity kernel/sched/fair.c:3512 [inline]
 [<ffffffff811e66ca>] enqueue_task_fair+0x2fa/0x2790 kernel/sched/fair.c:4695
 [<ffffffff811bdbad>] enqueue_task kernel/sched/core.c:858 [inline]
 [<ffffffff811bdbad>] activate_task+0x14d/0x280 kernel/sched/core.c:874
 [<ffffffff811bebdf>] ttwu_activate kernel/sched/core.c:1736 [inline]
 [<ffffffff811bebdf>] ttwu_do_activate.constprop.109+0xbf/0x1e0 kernel/sched/core.c:1789
 [<ffffffff811c1df0>] ttwu_queue kernel/sched/core.c:1934 [inline]
 [<ffffffff811c1df0>] try_to_wake_up+0x660/0xf00 kernel/sched/core.c:2068
 [<ffffffff811c274b>] wake_up_q+0xbb/0x130 kernel/sched/core.c:582
 [<ffffffff812ced4f>] futex_wake+0x3af/0x460 kernel/futex.c:1449
 [<ffffffff812d2cbd>] do_futex+0x26d/0x17f0 kernel/futex.c:3230
 [<ffffffff812d4430>] SYSC_futex kernel/futex.c:3286 [inline]
 [<ffffffff812d4430>] SyS_futex+0x1f0/0x300 kernel/futex.c:3254
 [<ffffffff838c8c65>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: 89 f2 48 c1 ea 03 4c 01 ea 49 8d bc 24 d8 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 c4 01 00 00 49 8b 9c 24 d8 00 00 00 <80> 3a 00 0f 85 8f 01 00 00 4a 03 1c f9 48 89 d8 48 c1 e8 03 42 
RIP  [<ffffffff81226f3c>] cpuacct_charge+0x14c/0x380 kernel/sched/cpuacct.c:247
 RSP <ffff8801b8e3f890>
CR2: fffffbfff37a7c80
---[ end trace a381403c7e0435a1 ]---