IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready
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 ffff8801d98f5900 by task syz-executor0/4314

CPU: 1 PID: 4314 Comm: syz-executor0 Not tainted 4.4.147-ga5fc665 #16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 e65eb4d87f98ca32 ffff8800b903fc78 ffffffff81e12a4d
 ffffea0007663d00 ffff8801d98f5900 0000000000000000 ffff8801d98f5900
 ffffffff82f1f9a0 ffff8800b903fcb0 ffffffff81517fd6 ffff8801d98f5900
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
 [<ffffffff814fbdc4>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff835a1204>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
 [<ffffffff835add3f>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509
 [<ffffffff82f1f876>] sock_release+0x96/0x1c0 net/socket.c:587
 [<ffffffff82f1f9b6>] sock_close+0x16/0x20 net/socket.c:1038
 [<ffffffff815253c5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81525905>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118e00f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff8100362d>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100362d>] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:253
 [<ffffffff8100708e>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline]
 [<ffffffff8100708e>] syscall_return_slowpath arch/x86/entry/common.c:349 [inline]
 [<ffffffff8100708e>] do_syscall_32_irqs_on arch/x86/entry/common.c:399 [inline]
 [<ffffffff8100708e>] do_fast_syscall_32+0x61e/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838ca5c3>] sysenter_flags_fixed+0xd/0x1a

Allocated by task 4314:
 [<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
 [<ffffffff814f7894>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff835a6649>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff835a6649>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff835a6649>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748
 [<ffffffff835ab350>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f24298>] SYSC_connect+0x1b8/0x300 net/socket.c:1558
 [<ffffffff82f26bd4>] SyS_connect+0x24/0x30 net/socket.c:1539
 [<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
 [<ffffffff838ca5c3>] sysenter_flags_fixed+0xd/0x1a

Freed by task 4313:
 [<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
 [<ffffffff814f8cc4>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f8cc4>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f8cc4>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f8cc4>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff835a35b0>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676
 [<ffffffff835a5969>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline]
 [<ffffffff835a5969>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279
 [<ffffffff835a647b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff83498481>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421
 [<ffffffff82f3516d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff83497135>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832fea9f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff83421730>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82f1f876>] sock_release+0x96/0x1c0 net/socket.c:587
 [<ffffffff82f1f9b6>] sock_close+0x16/0x20 net/socket.c:1038
 [<ffffffff815253c5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81525905>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118e00f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff8100362d>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100362d>] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:253
 [<ffffffff8100708e>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline]
 [<ffffffff8100708e>] syscall_return_slowpath arch/x86/entry/common.c:349 [inline]
 [<ffffffff8100708e>] do_syscall_32_irqs_on arch/x86/entry/common.c:399 [inline]
 [<ffffffff8100708e>] do_fast_syscall_32+0x61e/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838ca5c3>] sysenter_flags_fixed+0xd/0x1a

The buggy address belongs to the object at ffff8801d98f5900
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8801d98f5900, ffff8801d98f5b00)
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[   55.550747] kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
BUG: unable to handle kernel paging request at ffff8801d98f5b00
IP: [<ffff8801d98f5b00>] 0xffff8801d98f5b00
PGD 6330067 PUD 80000001c00001e3 
Oops: 0011 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3865 Comm: syz-executor0 Not tainted 4.4.147-ga5fc665 #16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c6f09800 task.stack: ffff8801d8ee0000
RIP: 0010:[<ffff8801d98f5b00>]  [<ffff8801d98f5b00>] 0xffff8801d98f5b00
RSP: 0018:ffff8801db207c70  EFLAGS: 00010006
RAX: ffff8801c6f09800 RBX: ffff8800b7760000 RCX: ffffffff82030627
RDX: 0000000000010100 RSI: ffffffff82030603 RDI: ffff8800b7760000
RBP: ffff8801db207c98 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff8801d98f5b00
R13: 0000000000000000 R14: 000000000000ffff R15: ffff8801d4b4ea30
FS:  0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:000000000987e900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffff8801d98f5b00 CR3: 00000001d8ce0000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8203060b ffff8801d4493f00 dffffc0000000000 ffffffff82030500
 0000000000000000 ffff8801db207cf0 ffffffff8126270c ffff8801db207cd8
 fffffbfff0940c40 ffff8801d4b4ea00 0000001e00000000 ffff8801d4b4ea00
Call Trace:
 <IRQ> 
 [<ffffffff8126270c>] handle_irq_event_percpu+0xec/0x970 kernel/irq/handle.c:146
 [<ffffffff81263037>] handle_irq_event+0xa7/0x140 kernel/irq/handle.c:194
 [<ffffffff8126c92f>] handle_edge_irq+0x1ff/0x900 kernel/irq/chip.c:623
 [<ffffffff81015a16>] generic_handle_irq_desc include/linux/irqdesc.h:140 [inline]
 [<ffffffff81015a16>] handle_irq+0x256/0x390 arch/x86/kernel/irq_64.c:78
 [<ffffffff838cb729>] do_IRQ+0x89/0x1c0 arch/x86/kernel/irq.c:239
 [<ffffffff838c97e0>] common_interrupt+0xa0/0xa0 arch/x86/entry/entry_64.S:596
 [<ffffffff81141a8d>] invoke_softirq kernel/softirq.c:350 [inline]
 [<ffffffff81141a8d>] irq_exit+0x10d/0x140 kernel/softirq.c:391
 [<ffffffff838cb8e1>] exiting_irq arch/x86/include/asm/apic.h:652 [inline]
 [<ffffffff838cb8e1>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:926
 [<ffffffff838ca820>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:741
 <EOI> 
 [<ffffffff8125f7de>] vprintk_emit+0x51e/0x840 kernel/printk/printk.c:1832
 [<ffffffff8125fb28>] vprintk+0x28/0x30 kernel/printk/printk.c:1843
 [<ffffffff8125fb4d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1844
 [<ffffffff81417848>] printk+0xaf/0xd7 kernel/printk/printk.c:1922
 [<ffffffff81125bf3>] kasan_die_handler.cold.3+0x1d/0x22 arch/x86/mm/kasan_init_64.c:59
 [<ffffffff811963f9>] notifier_call_chain+0xb9/0x1e0 kernel/notifier.c:93
 [<ffffffff81197a0f>] __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
 [<ffffffff81197a0f>] atomic_notifier_call_chain+0x7f/0x140 kernel/notifier.c:193
 [<ffffffff81197baf>] notify_die+0xdf/0x160 kernel/notifier.c:549
 [<ffffffff81010ffa>] do_general_protection+0x20a/0x2b0 arch/x86/kernel/traps.c:461
 [<ffffffff838c9fe8>] general_protection+0x28/0x30 arch/x86/entry/entry_64.S:1036
 [<ffffffff81c6d2d3>] selinux_task_wait+0x23/0x30 security/selinux/hooks.c:3763
 [<ffffffff81c524c3>] security_task_wait+0x73/0xb0 security/security.c:986
 [<ffffffff81139418>] wait_consider_task+0x298/0x35f0 kernel/exit.c:1326
 [<ffffffff8113cad4>] do_wait_thread kernel/exit.c:1439 [inline]
 [<ffffffff8113cad4>] do_wait+0x364/0xa30 kernel/exit.c:1510
 [<ffffffff8113da4b>] SYSC_wait4 kernel/exit.c:1641 [inline]
 [<ffffffff8113da4b>] SyS_wait4+0x12b/0x1f0 kernel/exit.c:1606
 [<ffffffff812f8477>] C_SYSC_wait4+0x237/0x280 kernel/compat.c:543
 [<ffffffff812f882c>] compat_SyS_wait4+0x2c/0x40 kernel/compat.c:536
 [<ffffffff81117565>] sys32_waitpid+0x25/0x30 arch/x86/ia32/sys_ia32.c:172
 [<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
 [<ffffffff838ca5c3>] sysenter_flags_fixed+0xd/0x1a
Code: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 <da> 10 00 00 48 01 60 f2 d9 10 00 00 49 01 80 d2 00 00 00 00 00 
RIP  [<ffff8801d98f5b00>] 0xffff8801d98f5b00
 RSP <ffff8801db207c70>
CR2: ffff8801d98f5b00
---[ end trace b1bef35502c8d132 ]---