==================================================================
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 ffff8800bba2d298 by task syz-executor7/8665

CPU: 0 PID: 8665 Comm: syz-executor7 Not tainted 4.4.152-ge15716b #24
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 00e029ce49af6010 ffff8801d3707548 ffffffff81e15fed
 ffffea0002ee8b40 ffff8800bba2d298 0000000000000000 ffff8800bba2d298
 0000000000001000 ffff8801d3707580 ffffffff8151b489 ffff8800bba2d298
Call Trace:
 [<ffffffff81e15fed>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e15fed>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8151b489>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff8151b7a8>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8151b7a8>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814fe734>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff83435efc>] ip6_dst_idev include/net/ip6_fib.h:141 [inline]
 [<ffffffff83435efc>] ip6_xmit+0x177c/0x1a00 net/ipv6/ip6_output.c:237
 [<ffffffff834f60c5>] inet6_csk_xmit+0x245/0x490 net/ipv6/inet6_connection_sock.c:176
 [<ffffffff835a570c>] l2tp_xmit_core net/l2tp/l2tp_core.c:1084 [inline]
 [<ffffffff835a570c>] l2tp_xmit_skb+0xb9c/0xe80 net/l2tp/l2tp_core.c:1179
 [<ffffffff835b1c60>] pppol2tp_sendmsg+0x4e0/0x7d0 net/l2tp/l2tp_ppp.c:355
 [<ffffffff82f2727c>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff82f2727c>] sock_sendmsg+0xcc/0x110 net/socket.c:648
 [<ffffffff82f28a41>] ___sys_sendmsg+0x441/0x880 net/socket.c:1975
 [<ffffffff82f2b0d4>] __sys_sendmmsg+0x1d4/0x2e0 net/socket.c:2053
 [<ffffffff83014b22>] C_SYSC_sendmmsg net/compat.c:728 [inline]
 [<ffffffff83014b22>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:725
 [<ffffffff81006d94>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d94>] do_fast_syscall_32+0x324/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838cdec3>] sysenter_flags_fixed+0xd/0x1a

Allocated by task 7381:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fd7d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fdab7>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fdab7>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814fe082>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff814f9b9e>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff814f9b9e>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff814f9b9e>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff814f9b9e>] kmem_cache_alloc+0xbe/0x2a0 mm/slub.c:2628
 [<ffffffff82fa5835>] dst_alloc+0xb5/0x1a0 net/core/dst.c:210
 [<ffffffff831f29c8>] rt_dst_alloc+0x78/0x430 net/ipv4/route.c:1478
 [<ffffffff831fbe8c>] __mkroute_output net/ipv4/route.c:2132 [inline]
 [<ffffffff831fbe8c>] __ip_route_output_key_hash+0x9ac/0x2380 net/ipv4/route.c:2344
 [<ffffffff831fe339>] __ip_route_output_key include/net/route.h:124 [inline]
 [<ffffffff831fe339>] ip_route_output_flow+0x29/0xa0 net/ipv4/route.c:2431
 [<ffffffff832da7c0>] udp_sendmsg+0x1480/0x1c70 net/ipv4/udp.c:1040
 [<ffffffff8349fbcd>] udpv6_sendmsg+0x12cd/0x24c0 net/ipv6/udp.c:1173
 [<ffffffff8330a633>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f2727c>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff82f2727c>] sock_sendmsg+0xcc/0x110 net/socket.c:648
 [<ffffffff82f28a41>] ___sys_sendmsg+0x441/0x880 net/socket.c:1975
 [<ffffffff82f2b0d4>] __sys_sendmmsg+0x1d4/0x2e0 net/socket.c:2053
 [<ffffffff83014b22>] C_SYSC_sendmmsg net/compat.c:728 [inline]
 [<ffffffff83014b22>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:725
 [<ffffffff81006d94>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d94>] do_fast_syscall_32+0x324/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838cdec3>] sysenter_flags_fixed+0xd/0x1a

Freed by task 3:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fd7d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fe102>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fe102>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814fb2ee>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814fb2ee>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814fb2ee>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814fb2ee>] kmem_cache_free+0xbe/0x340 mm/slub.c:2881
 [<ffffffff82fa4ae5>] dst_destroy.part.6+0x1f5/0x330 net/core/dst.c:270
 [<ffffffff82fa5165>] dst_destroy net/core/dst.c:252 [inline]
 [<ffffffff82fa5165>] dst_destroy_rcu+0x15/0x40 net/core/dst.c:295
 [<ffffffff81288d47>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff81288d47>] rcu_do_batch kernel/rcu/tree.c:2705 [inline]
 [<ffffffff81288d47>] invoke_rcu_callbacks kernel/rcu/tree.c:2973 [inline]
 [<ffffffff81288d47>] __rcu_process_callbacks kernel/rcu/tree.c:2940 [inline]
 [<ffffffff81288d47>] rcu_process_callbacks+0x927/0x1440 kernel/rcu/tree.c:2957
 [<ffffffff838cfa7c>] __do_softirq+0x22c/0xa1a kernel/softirq.c:273

The buggy address belongs to the object at ffff8800bba2d280
 which belongs to the cache ip_dst_cache of size 208
The buggy address is located 24 bytes inside of
 208-byte region [ffff8800bba2d280, ffff8800bba2d350)
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: 3892 Comm: syz-executor5 Not tainted 4.4.152-ge15716b #24
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bac71800 task.stack: ffff8801bd9c8000
RIP: 0010:[<ffffffff8132398d>]  [<ffffffff8132398d>] map_id_up kernel/user_namespace.c:209 [inline]
RIP: 0010:[<ffffffff8132398d>]  [<ffffffff8132398d>] from_kuid kernel/user_namespace.c:261 [inline]
RIP: 0010:[<ffffffff8132398d>]  [<ffffffff8132398d>] from_kuid_munged+0xad/0x2a0 kernel/user_namespace.c:286
RSP: 0000:ffff8801db307ba0  EFLAGS: 00010046
RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: ffff8800bac71800
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8801db307bd8
RBP: ffff8801db307c40 R08: ffff8800bac72100 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8800bac71800 R12: 0000000000000000
R13: 00000000ffffea00 R14: 00000000ffffea00 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000084d8900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000084d8914 CR3: 00000001d7ed8000 CR4: 00000000001606f0
Stack:
 1ffff1003b660f77 0000000000000000 ffff8800bac720e0 0000000041b58ab3
 ffffffff841e94a1 ffffffff813238e0 ffff8801db307c10 ffff8800ffffea00
 0000000000000046 ffff8800bac720e0 0000000000000046 ffff8801d298a400
Call Trace:
 <IRQ> 
 [<ffffffff82c414f7>] cpufreq_acct_update_power+0x207/0xd50 drivers/cpufreq/cpufreq_times.c:331
 [<ffffffff811d6adf>] account_user_time+0x16f/0x1d0 kernel/sched/cputime.c:171
 [<ffffffff811d79fc>] account_process_tick+0x11c/0x310 kernel/sched/cputime.c:504
 [<ffffffff8129d813>] update_process_times+0x23/0x70 kernel/time/timer.c:1425
 [<ffffffff812c81e5>] tick_sched_handle.isra.15+0x55/0xf0 kernel/time/tick-sched.c:151
 [<ffffffff812c8872>] tick_sched_timer+0x72/0x120 kernel/time/tick-sched.c:1097
 [<ffffffff812a0d9d>] __run_hrtimer kernel/time/hrtimer.c:1261 [inline]
 [<ffffffff812a0d9d>] __hrtimer_run_queues+0x3ad/0x1000 kernel/time/hrtimer.c:1325
 [<ffffffff812a2511>] hrtimer_interrupt+0x1b1/0x430 kernel/time/hrtimer.c:1359
 [<ffffffff810af544>] local_apic_timer_interrupt+0x74/0xa0 arch/x86/kernel/apic/apic.c:901
 [<ffffffff838cf1dc>] smp_apic_timer_interrupt+0x7c/0xa0 arch/x86/kernel/apic/apic.c:925
 [<ffffffff838ce120>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:741
 <EOI> 
Code: b6 04 18 3c 03 7f 08 84 c0 0f 85 e5 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b b5 68 ff ff ff 44 8b 6d 98 48 89 f2 48 c1 ea 03 <0f> b6 14 02 48 89 f0 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 
RIP  [<ffffffff8132398d>] map_id_up kernel/user_namespace.c:209 [inline]
RIP  [<ffffffff8132398d>] from_kuid kernel/user_namespace.c:261 [inline]
RIP  [<ffffffff8132398d>] from_kuid_munged+0xad/0x2a0 kernel/user_namespace.c:286
 RSP <ffff8801db307ba0>
---[ end trace e3e5df05f2356579 ]---