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 ffff8801d6e00a00 by task syz-executor0/4193

CPU: 1 PID: 4193 Comm: syz-executor0 Not tainted 4.4.135-ge75204c #53
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 b50ca959bcc23620 ffff8800b952fc78 ffffffff81e0ed0d
 ffffea00075b8000 ffff8801d6e00a00 0000000000000000 ffff8801d6e00a00
 ffffffff82f1a1e0 ffff8800b952fcb0 ffffffff81515946 ffff8801d6e00a00
Call Trace:
 [<ffffffff81e0ed0d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0ed0d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81515946>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff81515c65>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81515c65>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9734>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff8359ad94>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
 [<ffffffff835a78cf>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509
 [<ffffffff82f1a0b6>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a1f6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81522d35>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81523275>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bd7f>] 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:252
 [<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
 [<ffffffff838c40aa>] sysenter_flags_fixed+0xd/0x17

Allocated by task 4193:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8803>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8ae7>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8ae7>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f5204>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff835a01d9>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff835a01d9>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff835a01d9>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748
 [<ffffffff835a4ee0>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f1ead8>] SYSC_connect+0x1b8/0x300 net/socket.c:1557
 [<ffffffff82f21414>] 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
 [<ffffffff838c40aa>] sysenter_flags_fixed+0xd/0x17

Freed by task 4191:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8803>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f9132>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f9132>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f6634>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f6634>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f6634>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f6634>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff8359d140>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676
 [<ffffffff8359f4f9>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline]
 [<ffffffff8359f4f9>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279
 [<ffffffff835a000b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff832cbec8>] udp_destroy_sock+0x118/0x1a0 net/ipv4/udp.c:2056
 [<ffffffff82f2f98d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff832c9ed5>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832f8c5f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff82f1a0b6>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a1f6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81522d35>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81523275>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bd7f>] 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:252
 [<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
 [<ffffffff838c40aa>] sysenter_flags_fixed+0xd/0x17

The buggy address belongs to the object at ffff8801d6e00a00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8801d6e00a00, ffff8801d6e00c00)
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: 0 PID: 3850 Comm: syz-executor0 Not tainted 4.4.135-ge75204c #53
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c6ce8000 task.stack: ffff8801d8c20000
RIP: 0010:[<ffffffff8122f624>]  [<ffffffff8122f624>] __lock_acquire+0x5f4/0x5270 kernel/locking/lockdep.c:3100
RSP: 0018:ffff8801d8c278b0  EFLAGS: 00010006
RAX: 0000000000000000 RBX: 48000000a8ec8148 RCX: 1ffffffff02919ee
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff8148cf77
RBP: ffff8801d8c27a48 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff83a44860 R11: ffff8801c6ce8000 R12: 0000000000000000
R13: ffffffff8148cf6f R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000ffcd6e80 CR3: 00000001ce425000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801c6ce8901 0000000000000001 ffff8801d8c27a70 0000000000000046
 ffff8801d8c278c8 ffffffff849f4380 ffff8801d8c27900 ffffffff8122e8bb
 0000000000000296 ffffffff849f47c0 ffff8801d087f598 dffffc0000000000
Call Trace:
 [<ffffffff81235a7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff838bdb31>] down_write+0x41/0xa0 kernel/locking/rwsem.c:49
 [<ffffffff814b9fa8>] lock_anon_vma_root mm/rmap.c:234 [inline]
 [<ffffffff814b9fa8>] unlink_anon_vmas+0x148/0x640 mm/rmap.c:384
 [<ffffffff814946ad>] free_pgtables+0x21d/0x330 mm/memory.c:554
 [<ffffffff814b0228>] exit_mmap+0x1d8/0x3a0 mm/mmap.c:2928
 [<ffffffff81125508>] __mmput kernel/fork.c:715 [inline]
 [<ffffffff81125508>] mmput+0xf8/0x2d0 kernel/fork.c:735
 [<ffffffff81135178>] exit_mm kernel/exit.c:444 [inline]
 [<ffffffff81135178>] do_exit+0x8d8/0x26b0 kernel/exit.c:746
 [<ffffffff8113b1d1>] do_group_exit+0x111/0x330 kernel/exit.c:889
 [<ffffffff8113b40d>] SYSC_exit_group kernel/exit.c:900 [inline]
 [<ffffffff8113b40d>] 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
 [<ffffffff838c40aa>] sysenter_flags_fixed+0xd/0x17
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  [<ffffffff8122f624>] __lock_acquire+0x5f4/0x5270 kernel/locking/lockdep.c:3100
 RSP <ffff8801d8c278b0>
---[ end trace 20381e71bb173d89 ]---