IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready
random: nonblocking pool is initialized
IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
==================================================================
BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
Read of size 4 at addr ffff8800b672ef00 by task syz-executor0/4789

CPU: 1 PID: 4789 Comm: syz-executor0 Not tainted 4.4.133-g3f51ea2 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 d13ac9aebdfb07d7 ffff8801d2807868 ffffffff81e0e4cd
 ffffea0002d9cb80 ffff8800b672ef00 0000000000000000 ffff8800b672ef00
 ffffffff82f191d0 ffff8801d28078a0 ffffffff815154cc ffff8800b672ef00
Call Trace:
 [<ffffffff81e0e4cd>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0e4cd>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff815154cc>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff815157eb>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff815157eb>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f92c4>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff835995c4>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
 [<ffffffff835a60ff>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509
 [<ffffffff82f190a6>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f191e6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff815228b5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81522df5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bc3f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff81135175>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81135175>] do_exit+0x9e5/0x26b0 kernel/exit.c:759
 [<ffffffff8113b0c1>] do_group_exit+0x111/0x330 kernel/exit.c:889
 [<ffffffff8115e49c>] get_signal+0x4ec/0x14b0 kernel/signal.c:2317
 [<ffffffff8100e02b>] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712
 [<ffffffff8100360a>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:248
 [<ffffffff81007090>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81007090>] syscall_return_slowpath arch/x86/entry/common.c:348 [inline]
 [<ffffffff81007090>] do_syscall_32_irqs_on arch/x86/entry/common.c:398 [inline]
 [<ffffffff81007090>] do_fast_syscall_32+0x620/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c28aa>] sysenter_flags_fixed+0xd/0x17

Allocated by task 4785:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8393>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8677>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8677>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f4d94>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff8359ea09>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff8359ea09>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff8359ea09>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748
 [<ffffffff835a3710>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f1dac8>] SYSC_connect+0x1b8/0x300 net/socket.c:1557
 [<ffffffff82f20404>] SyS_connect+0x24/0x30 net/socket.c:1538
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c28aa>] sysenter_flags_fixed+0xd/0x17

Freed by task 4777:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8393>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8cc2>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8cc2>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f61c4>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f61c4>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f61c4>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f61c4>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff8359b970>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676
 [<ffffffff8359dd29>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline]
 [<ffffffff8359dd29>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279
 [<ffffffff8359e83b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff83490de1>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421
 [<ffffffff82f2e97d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff8348fa95>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832f75ef>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff8341a1c0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82f190a6>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f191e6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff815228b5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81522df5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bc3f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff81135175>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81135175>] do_exit+0x9e5/0x26b0 kernel/exit.c:759
 [<ffffffff8113b0c1>] do_group_exit+0x111/0x330 kernel/exit.c:889
 [<ffffffff8113b2fd>] SYSC_exit_group kernel/exit.c:900 [inline]
 [<ffffffff8113b2fd>] SyS_exit_group+0x1d/0x20 kernel/exit.c:898
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c28aa>] sysenter_flags_fixed+0xd/0x17

The buggy address belongs to the object at ffff8800b672ef00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8800b672ef00, ffff8800b672f100)
The buggy address belongs to the page:
PANIC: double fault, error_code: 0x0
CPU: 1 PID: 4789 Comm: syz-executor0 Not tainted 4.4.133-g3f51ea2 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d3a86000 task.stack: ffff8801d2800000
RIP: 0010:[<ffffffff8148cbb6>]  [<ffffffff8148cbb6>] dump_page_badflags+0x6/0x70 mm/debug.c:84
RSP: 0018:ffff880100000000  EFLAGS: 00010046
RAX: ffff8801d3a86000 RBX: ffffea0002d9cb80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff83aa9be0 RDI: ffffea0002d9cb80
RBP: ffff880100000008 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff858ed134 R12: 0000000000000000
R13: ffffffff83aa9be0 R14: ffff8800b672ef00 R15: ffff8800b672f100
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffff8800fffffff8 CR3: 00000000b1f21000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:

Call Trace:
 <UNK> 
Code: 48 69 c0 80 06 00 00 f0 48 ff 80 68 3e 9f 84 5b 5d c3 48 89 df e8 2b c7 06 00 eb dd 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 <41> 56 41 55 49 89 f5 41 54 49 89 d4 53 48 89 fb 48 83 ec 08 e8