random: sshd: uninitialized urandom read (32 bytes read, 39 bits of entropy available)
random: sshd: uninitialized urandom read (32 bytes read, 39 bits of entropy available)
random: nonblocking pool is initialized
==================================================================
BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
Read of size 4 at addr ffff8800bb858500 by task syz-executor964/3851

CPU: 1 PID: 3851 Comm: syz-executor964 Not tainted 4.4.131-gaa3863d #41
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 8b55997199635a46 ffff8801d956fcc0 ffffffff81e0df8d
 ffffea0002ee1600 ffff8800bb858500 0000000000000000 ffff8800bb858500
 ffffffff82f18dc0 ffff8801d956fcf8 ffffffff8151520c ffff8800bb858500
Call Trace:
 [<ffffffff81e0df8d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0df8d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8151520c>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff8151552b>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8151552b>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9004>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff83598894>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
 [<ffffffff835a53cf>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509
 [<ffffffff82f18c96>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f18dd6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff815225f5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81522b35>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bb8f>] 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
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff838bfff5>] int_ret_from_sys_call+0x25/0xa3

Allocated by task 3850:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f80d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f83b7>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f83b7>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f4ad4>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff8359dcd9>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff8359dcd9>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff8359dcd9>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748
 [<ffffffff835a29e0>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f1d6b8>] SYSC_connect+0x1b8/0x300 net/socket.c:1557
 [<ffffffff82f1fff4>] SyS_connect+0x24/0x30 net/socket.c:1538
 [<ffffffff838bfe65>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 3850:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f80d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8a02>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8a02>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f5f04>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f5f04>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f5f04>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f5f04>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff8359ac40>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676
 [<ffffffff8359cff9>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline]
 [<ffffffff8359cff9>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279
 [<ffffffff8359db0b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff83490101>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421
 [<ffffffff82f2e56d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff8348edb5>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832f6a6f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff83419600>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82f18c96>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f18dd6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff815225f5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81522b35>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bb8f>] 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
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff838bfff5>] int_ret_from_sys_call+0x25/0xa3

The buggy address belongs to the object at ffff8800bb858500
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8800bb858500, ffff8800bb858700)
The buggy address belongs to the page:
BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<          (null)>]           (null)
PGD ad8fa067 PUD b2e88067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.131-gaa3863d #41
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84417840 task.stack: ffffffff84400000
RIP: 0010:[<0000000000000000>]  [<          (null)>]           (null)
RSP: 0018:ffff8801db207e80  EFLAGS: 00010086
RAX: 0000000000000000 RBX: ffff8801d4b74900 RCX: ffffffff8126d2d7
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8801d4b74900
RBP: ffff8801db207e98 R08: ffffffff853301b0 R09: 0000000000000001
R10: 0000000000000001 R11: ffffffff84417840 R12: ffff8800bb858700
R13: dffffc0000000000 R14: ffff8801d456ca74 R15: ffff8801d456ca30
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000b5bd5000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8126d2c6 ffff8801d456ca00 ffff8801d456ca74 ffff8801db207f00
 ffffffff8126a3ef ffffffff84418118 ffff8801d456ca38 ffff8801d456ca68
 ffff8801d456ca20 ffff8801d456caa0 ffffffff811955a8 ffffffff84407d18
Call Trace:
 <IRQ> 
 [<ffffffff8126a3ef>] handle_edge_irq+0x1af/0x900 kernel/irq/chip.c:604
 [<ffffffff81015b06>] generic_handle_irq_desc include/linux/irqdesc.h:140 [inline]
 [<ffffffff81015b06>] handle_irq+0x256/0x390 arch/x86/kernel/irq_64.c:78
 [<ffffffff838c28d9>] do_IRQ+0x89/0x1c0 arch/x86/kernel/irq.c:239
 [<ffffffff838c09e0>] common_interrupt+0xa0/0xa0 arch/x86/entry/entry_64.S:596
 <EOI> 
 [<ffffffff81025da5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81025da5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
 [<ffffffff810272f0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:281
 [<ffffffff8121b9e7>] default_idle_call+0x57/0x70 kernel/sched/idle.c:93
 [<ffffffff8121c18f>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff8121c18f>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff8121c18f>] cpu_startup_entry+0x6af/0x780 kernel/sched/idle.c:301
 [<ffffffff838acfb1>] rest_init+0x188/0x18e init/main.c:410
 [<ffffffff84a4b8a1>] start_kernel+0x6b3/0x6e7 init/main.c:682
 [<ffffffff84a4a30f>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196
 [<ffffffff84a4a450>] x86_64_start_kernel+0x13f/0x162 arch/x86/kernel/head64.c:185
Code:  Bad RIP value.
RIP  [<          (null)>]           (null)
 RSP <ffff8801db207e80>
CR2: 0000000000000000
---[ end trace f6f03e18dab78880 ]---