IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes 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 ffff8800bad2f900 by task syz-executor0/8372

CPU: 0 PID: 8372 Comm: syz-executor0 Not tainted 4.4.145-g2241aa9 #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 5ec08ceeab372747 ffff8800aec2f8b8 ffffffff81e123cd
 ffffea0002eb4b80 ffff8800bad2f900 0000000000000000 ffff8800bad2f900
 ffffffff82f1eea0 ffff8800aec2f8f0 ffffffff81517d66 ffff8800bad2f900
Call Trace:
 [<ffffffff81e123cd>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e123cd>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81517d66>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff81518085>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81518085>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814fbb54>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff835a0aa4>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
 [<ffffffff835ad5df>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509
 [<ffffffff82f1ed76>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1eeb6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81525155>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81525695>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118e00f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff81137475>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81137475>] do_exit+0x9e5/0x26b0 kernel/exit.c:755
 [<ffffffff8113d3b1>] do_group_exit+0x111/0x330 kernel/exit.c:885
 [<ffffffff811607ac>] get_signal+0x4ec/0x14b0 kernel/signal.c:2321
 [<ffffffff8100df4b>] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712
 [<ffffffff8100360a>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:249
 [<ffffffff81006363>] prepare_exit_to_usermode+0xe3/0x100 arch/x86/entry/common.c:284
 [<ffffffff838c9088>] retint_user+0x8/0x3c

Allocated by task 8363:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fac23>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814faf07>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814faf07>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f7624>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff835a5ee9>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff835a5ee9>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff835a5ee9>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748
 [<ffffffff835aabf0>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f23798>] SYSC_connect+0x1b8/0x300 net/socket.c:1557
 [<ffffffff82f260d4>] SyS_connect+0x24/0x30 net/socket.c:1538
 [<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
 [<ffffffff838c9e43>] sysenter_flags_fixed+0xd/0x1a

Freed by task 8344:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fac23>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fb552>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fb552>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f8a54>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f8a54>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f8a54>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f8a54>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff835a2e50>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676
 [<ffffffff835a5209>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline]
 [<ffffffff835a5209>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279
 [<ffffffff835a5d1b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff83497d21>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421
 [<ffffffff82f3465d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff834969d5>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832fe2cf>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff83420fd0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82f1ed76>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1eeb6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81525155>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81525695>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118e00f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff81137475>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81137475>] do_exit+0x9e5/0x26b0 kernel/exit.c:755
 [<ffffffff8113d3b1>] do_group_exit+0x111/0x330 kernel/exit.c:885
 [<ffffffff811607ac>] get_signal+0x4ec/0x14b0 kernel/signal.c:2321
 [<ffffffff8100df4b>] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712
 [<ffffffff8100360a>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:249
 [<ffffffff81006363>] prepare_exit_to_usermode+0xe3/0x100 arch/x86/entry/common.c:284
 [<ffffffff838c9088>] retint_user+0x8/0x3c

The buggy address belongs to the object at ffff8800bad2f900
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8800bad2f900, ffff8800bad2fb00)
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: 4084 Comm: kpktgend_1 Not tainted 4.4.145-g2241aa9 #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800b9af0000 task.stack: ffff8800b9a58000
RIP: 0010:[<ffffffff812318b4>]  [<ffffffff812318b4>] __lock_acquire+0x5f4/0x5270 kernel/locking/lockdep.c:3100
RSP: 0000:ffff8800b9a5f9a0  EFLAGS: 00010086
RAX: 0000000000000000 RBX: dead4ead00000000 RCX: 1ffff100175a6069
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff8800bad30348
RBP: ffff8800b9a5fb38 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff83a456e0 R11: ffff8800b9af0000 R12: 0000000000000000
R13: ffff8800bad30340 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000008350038 CR3: 00000000b6740000 CR4: 00000000001606f0
Stack:
 0000000041b58ab3 ffffffff841ec738 ffffffff812312c0 ffff8800b9af08e0
 000000000000007b ffff8801d99c85f8 dffffc0000000000 ffff8800b9af0930
 ffff8800b9af0908 0000000000000002 ffff8800b9a5fab0 0000000000000046
Call Trace:
 [<ffffffff81237d0e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff838c811e>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline]
 [<ffffffff838c811e>] _raw_spin_lock_irqsave+0x4e/0x70 kernel/locking/spinlock.c:159
 [<ffffffff811c17bc>] try_to_wake_up+0x2c/0xf00 kernel/sched/core.c:1974
 [<ffffffff811c27d5>] wake_up_process+0x15/0x20 kernel/sched/core.c:2142
 [<ffffffff811389f0>] exit_notify kernel/exit.c:623 [inline]
 [<ffffffff811389f0>] do_exit+0x1f60/0x26b0 kernel/exit.c:776
 [<ffffffff81192b9b>] kthread+0x21b/0x300 kernel/kthread.c:214
 [<ffffffff838c8915>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
Code: 00 fc ff df 44 89 e0 49 8d 7c c5 08 48 89 f9 48 c1 e9 03 80 3c 11 00 0f 85 94 36 00 00 49 8b 5c c5 08 48 85 db 0f 84 21 22 00 00 <f0> ff 83 98 01 00 00 49 8d 83 d8 08 00 00 48 89 c2 48 89 44 24 
RIP  [<ffffffff812318b4>] __lock_acquire+0x5f4/0x5270 kernel/locking/lockdep.c:3100
 RSP <ffff8800b9a5f9a0>
---[ end trace d61090f1d8a5fb22 ]---