random: sshd: uninitialized urandom read (32 bytes read, 36 bits of entropy available)
random: sshd: uninitialized urandom read (32 bytes read, 121 bits of entropy available)
random: sshd: uninitialized urandom read (32 bytes read, 127 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 ffff8801cf1adb80 by task syz-executor116/3657

CPU: 0 PID: 3657 Comm: syz-executor116 Not tainted 4.4.134-gcb3afe1 #53
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 20c3dbf96476a9c3 ffff8801cef5fcc0 ffffffff81e0f02d
 ffffea00073c6b00 ffff8801cf1adb80 0000000000000000 ffff8801cf1adb80
 ffffffff82f1a500 ffff8801cef5fcf8 ffffffff81515946 ffff8801cf1adb80
Call Trace:
 [<ffffffff81e0f02d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0f02d>] 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
 [<ffffffff8359b0b4>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
 [<ffffffff835a7bef>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509
 [<ffffffff82f1a3d6>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a516>] 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
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff838c2c35>] int_ret_from_sys_call+0x25/0xa3

Allocated by task 3654:
 [<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
 [<ffffffff835a04f9>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff835a04f9>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff835a04f9>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748
 [<ffffffff835a5200>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f1edf8>] SYSC_connect+0x1b8/0x300 net/socket.c:1557
 [<ffffffff82f21734>] SyS_connect+0x24/0x30 net/socket.c:1538
 [<ffffffff838c2aa5>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 3654:
 [<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
 [<ffffffff8359d460>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676
 [<ffffffff8359f819>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline]
 [<ffffffff8359f819>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279
 [<ffffffff835a032b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff832cc1e8>] udp_destroy_sock+0x118/0x1a0 net/ipv4/udp.c:2056
 [<ffffffff82f2fcad>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff832ca1f5>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832f8f7f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff82f1a3d6>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a516>] 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
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff838c2c35>] int_ret_from_sys_call+0x25/0xa3

The buggy address belongs to the object at ffff8801cf1adb80
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8801cf1adb80, ffff8801cf1add80)
The buggy address belongs to the page:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory accessBUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff8181acde>] lock_buffer include/linux/buffer_head.h:352 [inline]
IP: [<ffffffff8181acde>] do_get_write_access+0x1be/0x13b0 fs/jbd2/transaction.c:835
PGD 1cfa88067 PUD 1cfad1067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 3658 Comm: init Not tainted 4.4.134-gcb3afe1 #53
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801cf5cb000 task.stack: ffff8801cefa8000
RIP: 0010:[<ffffffff8181acde>]  [<ffffffff8181acde>] lock_buffer include/linux/buffer_head.h:352 [inline]
RIP: 0010:[<ffffffff8181acde>]  [<ffffffff8181acde>] do_get_write_access+0x1be/0x13b0 fs/jbd2/transaction.c:835
RSP: 0018:ffff8801cefaf740  EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000e4a
RDX: 1ffff10039eb96a8 RSI: ffffffff844bdba0 RDI: ffff8801cf5cb540
RBP: ffff8801cefaf838 R08: ffff8801cf5cb978 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8801cf5cb000 R12: dffffc0000000000
R13: ffff8800ba09b738 R14: 00000000ffff9615 R15: ffff8801ce024580
FS:  00007f1a4903c7a0(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001d2258000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801cefaf800 0000000000000246 fffffbfff0941195 0000000000000000
 ffff8801ce21167c 1ffff10039df5ef2 ffff8801d3d96600 ffff8801ce211660
 ffff880100000000 ffff8800b14a0000 0000000041b58ab3 ffffffff841d91bb
Call Trace:
 [<ffffffff8181bf1d>] jbd2_journal_get_write_access+0x4d/0xa0 fs/jbd2/transaction.c:1088
 [<ffffffff817991cc>] __ext4_journal_get_write_access+0x4c/0x90 fs/ext4/ext4_jbd2.c:164
 [<ffffffff816e8723>] ext4_reserve_inode_write+0xe3/0x180 fs/ext4/inode.c:5220
 [<ffffffff816e8933>] ext4_mark_inode_dirty+0x173/0xb80 fs/ext4/inode.c:5286
 [<ffffffff816f6a4b>] ext4_dirty_inode+0x7b/0xa0 fs/ext4/inode.c:5348
 [<ffffffff8159f9f8>] __mark_inode_dirty+0x408/0x1360 fs/fs-writeback.c:2055
 [<ffffffff81570255>] generic_update_time+0x1a5/0x270 fs/inode.c:1578
 [<ffffffff81570685>] update_time fs/inode.c:1594 [inline]
 [<ffffffff81570685>] file_update_time+0x285/0x3c0 fs/inode.c:1798
 [<ffffffff81423078>] __generic_file_write_iter+0x1c8/0x550 mm/filemap.c:2653
 [<ffffffff816c5585>] ext4_file_write_iter+0x405/0xc60 fs/ext4/file.c:171
 [<ffffffff8151cd3d>] new_sync_write fs/read_write.c:478 [inline]
 [<ffffffff8151cd3d>] __vfs_write+0x30d/0x3f0 fs/read_write.c:491
 [<ffffffff8151e921>] vfs_write+0x191/0x4e0 fs/read_write.c:538
 [<ffffffff81520f29>] SYSC_write fs/read_write.c:585 [inline]
 [<ffffffff81520f29>] SyS_write+0xd9/0x1c0 fs/read_write.c:577
 [<ffffffff838c2aa5>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: 8b 1f 48 c1 e8 03 42 80 3c 20 00 0f 85 0b 0f 00 00 31 d2 be 60 01 00 00 48 c7 c7 60 98 af 83 4c 8b 35 27 e3 be 02 e8 f2 99 98 ff <f0> 0f ba 2b 02 0f 82 24 04 00 00 e8 c2 67 b3 ff e8 bd 67 b3 ff 
RIP  [<ffffffff8181acde>] lock_buffer include/linux/buffer_head.h:352 [inline]
RIP  [<ffffffff8181acde>] do_get_write_access+0x1be/0x13b0 fs/jbd2/transaction.c:835
 RSP <ffff8801cefaf740>
CR2: 0000000000000000
BUG: unable to handle kernel paging request at fffffffdfd782880
IP: [<ffffffff81224cb5>] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247
PGD 440f067 PUD 0 
Oops: 0000 [#2] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 3658 Comm: init Tainted: G      D         4.4.134-gcb3afe1 #53
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801cf5cb000 task.stack: ffff8801cefa8000
RIP: 0010:[<ffffffff81224cb5>]  [<ffffffff81224cb5>] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247
RSP: 0018:ffff8801db307a00  EFLAGS: 00010046
RAX: 1ffffffff089500f RBX: 0000000000018528 RCX: ffffffff84a14c80
RDX: fffffbffbfaf0510 RSI: fffffffdfd782880 RDI: ffffffff844a8078
RBP: ffff8801db307a40 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8801cf5cb000 R12: ffffffff844a7fa0
R13: dffffc0000000000 R14: 000000001bff1783 R15: ffffffffcf1adb80
FS:  00007f1a4903c7a0(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffdfd782880 CR3: 00000001d2258000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81224bc0 ffffffff811f10ac ffff88021fffd05b ffff8800b3263060
 ffff8800b3263000 000000001bff1783 ffff8800b32630b0 0000000000000000
 ffff8801db307a88 ffffffff811d9239 0000000000000005 ffff8801db21f4d8
Call Trace:
 <IRQ> 
 [<ffffffff811d9239>] update_curr+0x2c9/0x6d0 kernel/sched/fair.c:882
 [<ffffffff811e443a>] enqueue_entity kernel/sched/fair.c:3512 [inline]
 [<ffffffff811e443a>] enqueue_task_fair+0x2fa/0x2790 kernel/sched/fair.c:4695
 [<ffffffff811bb91d>] enqueue_task kernel/sched/core.c:858 [inline]
 [<ffffffff811bb91d>] activate_task+0x14d/0x280 kernel/sched/core.c:874
 [<ffffffff811bc94f>] ttwu_activate kernel/sched/core.c:1736 [inline]
 [<ffffffff811bc94f>] ttwu_do_activate.constprop.109+0xbf/0x1e0 kernel/sched/core.c:1789
 [<ffffffff811bfb60>] ttwu_queue kernel/sched/core.c:1934 [inline]
 [<ffffffff811bfb60>] try_to_wake_up+0x660/0xf00 kernel/sched/core.c:2068
 [<ffffffff811c0585>] default_wake_function+0x35/0x50 kernel/sched/core.c:3498
 [<ffffffff8121b383>] autoremove_wake_function+0x13/0x90 kernel/sched/wait.c:293
 [<ffffffff81219ed6>] __wake_up_common+0xb6/0x150 kernel/sched/wait.c:73
 [<ffffffff81219fa4>] __wake_up+0x34/0x50 kernel/sched/wait.c:95
 [<ffffffff8125e8f0>] wake_up_klogd_work_func+0x80/0x90 kernel/printk/printk.c:2736
 [<ffffffff813d5427>] irq_work_run_list+0xd7/0x140 kernel/irq_work.c:156
 [<ffffffff813d5aa6>] irq_work_tick+0x116/0x170 kernel/irq_work.c:182
 [<ffffffff8129a809>] update_process_times+0x69/0x70 kernel/time/timer.c:1430
 [<ffffffff812c5195>] tick_sched_handle.isra.15+0x55/0xf0 kernel/time/tick-sched.c:151
 [<ffffffff812c5822>] tick_sched_timer+0x72/0x120 kernel/time/tick-sched.c:1097
 [<ffffffff8129dd4d>] __run_hrtimer kernel/time/hrtimer.c:1261 [inline]
 [<ffffffff8129dd4d>] __hrtimer_run_queues+0x3ad/0x1000 kernel/time/hrtimer.c:1325
 [<ffffffff8129f4c1>] hrtimer_interrupt+0x1b1/0x430 kernel/time/hrtimer.c:1359
 [<ffffffff810ad614>] local_apic_timer_interrupt+0x74/0xa0 arch/x86/kernel/apic/apic.c:901
 [<ffffffff838c56cc>] smp_apic_timer_interrupt+0x7c/0xa0 arch/x86/kernel/apic/apic.c:925
 [<ffffffff838c4610>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:741
 <EOI> 
 [<ffffffff810d6bf8>] no_context+0x378/0x7b0 arch/x86/mm/fault.c:735
 [<ffffffff810d7290>] __bad_area_nosemaphore+0x260/0x310 arch/x86/mm/fault.c:815
 [<ffffffff810d73e6>] __bad_area arch/x86/mm/fault.c:837 [inline]
 [<ffffffff810d73e6>] bad_area+0x66/0x80 arch/x86/mm/fault.c:843
 [<ffffffff810d7ea7>] __do_page_fault+0x767/0xa10 arch/x86/mm/fault.c:1225
 [<ffffffff810d8177>] do_page_fault+0x27/0x30 arch/x86/mm/fault.c:1308
 [<ffffffff838c3e88>] page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1037
 [<ffffffff8181bf1d>] jbd2_journal_get_write_access+0x4d/0xa0 fs/jbd2/transaction.c:1088
 [<ffffffff817991cc>] __ext4_journal_get_write_access+0x4c/0x90 fs/ext4/ext4_jbd2.c:164
 [<ffffffff816e8723>] ext4_reserve_inode_write+0xe3/0x180 fs/ext4/inode.c:5220
 [<ffffffff816e8933>] ext4_mark_inode_dirty+0x173/0xb80 fs/ext4/inode.c:5286
 [<ffffffff816f6a4b>] ext4_dirty_inode+0x7b/0xa0 fs/ext4/inode.c:5348
 [<ffffffff8159f9f8>] __mark_inode_dirty+0x408/0x1360 fs/fs-writeback.c:2055
 [<ffffffff81570255>] generic_update_time+0x1a5/0x270 fs/inode.c:1578
 [<ffffffff81570685>] update_time fs/inode.c:1594 [inline]
 [<ffffffff81570685>] file_update_time+0x285/0x3c0 fs/inode.c:1798
 [<ffffffff81423078>] __generic_file_write_iter+0x1c8/0x550 mm/filemap.c:2653
 [<ffffffff816c5585>] ext4_file_write_iter+0x405/0xc60 fs/ext4/file.c:171
 [<ffffffff8151cd3d>] new_sync_write fs/read_write.c:478 [inline]
 [<ffffffff8151cd3d>] __vfs_write+0x30d/0x3f0 fs/read_write.c:491
 [<ffffffff8151e921>] vfs_write+0x191/0x4e0 fs/read_write.c:538
 [<ffffffff81520f29>] SYSC_write fs/read_write.c:585 [inline]
 [<ffffffff81520f29>] SyS_write+0xd9/0x1c0 fs/read_write.c:577
 [<ffffffff838c2aa5>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: 49 8d bc 24 d8 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 c4 01 00 00 49 8b 9c 24 d8 00 00 00 80 3a 00 0f 85 8f 01 00 00 <4a> 03 1c f9 48 89 d8 48 c1 e8 03 42 80 3c 28 00 0f 85 be 01 00 
RIP  [<ffffffff81224cb5>] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247
 RSP <ffff8801db307a00>
CR2: fffffffdfd782880
---[ end trace e19391e26d4adb99 ]---