[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.337709] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.870667] random: sshd: uninitialized urandom read (32 bytes read) [ 27.298996] random: sshd: uninitialized urandom read (32 bytes read) [ 27.993742] random: sshd: uninitialized urandom read (32 bytes read) [ 28.115821] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.15' (ECDSA) to the list of known hosts. [ 33.532614] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.742835] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.751082] IP: [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 33.757788] PGD 1bcd54067 [ 33.760430] PUD 1ba87f067 PMD 0 [ 33.763912] [ 33.765529] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.769995] Dumping ftrace buffer: [ 33.773504] (ftrace buffer empty) [ 33.777186] Modules linked in: [ 33.780468] CPU: 1 PID: 3813 Comm: syz-executor086 Not tainted 4.9.113-g47bbcd6 #10 [ 33.788242] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.797578] task: ffff8801b568e000 task.stack: ffff8801b51c8000 [ 33.803605] RIP: 0010:[<ffffffff836bcd0c>] [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 33.812451] RSP: 0018:ffff8801b51cfca0 EFLAGS: 00010246 [ 33.817870] RAX: dffffc0000000000 RBX: ffff8801b571db80 RCX: 0000000000000000 [ 33.825112] RDX: 1ffff10036a93260 RSI: ffffffff836bcce1 RDI: ffff8801b5499300 [ 33.832352] RBP: ffff8801b51cfcc0 R08: ffff8801b568e8e8 R09: 0000000000000000 [ 33.839594] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5499180 [ 33.846837] R13: ffff8801b571db88 R14: 0000000000000000 R15: ffffffff83013be0 [ 33.854089] FS: 0000000000981880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 33.862296] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.868149] CR2: 0000000000000080 CR3: 00000001ca5b1000 CR4: 00000000001606f0 [ 33.875394] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 33.882645] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 33.889893] Stack: [ 33.892014] ffff8801d97b9100 ffff8801b571db80 ffff8801d97b94d0 ffff8801d97b93d8 [ 33.899998] ffff8801b51cfce8 ffffffff836c45f2 ffff8801d97b9540 ffff8801d97b9100 [ 33.908004] ffffffff836c4520 ffff8801b51cfd20 ffffffff83021095 ffff8801d97b9540 [ 33.915989] Call Trace: [ 33.918552] [<ffffffff836c45f2>] pppol2tp_session_destruct+0xd2/0x110 [ 33.925191] [<ffffffff836c4520>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.931491] [<ffffffff83021095>] __sk_destruct+0x55/0x590 [ 33.937091] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 33.942860] [<ffffffff83028b23>] sk_destruct+0x63/0x80 [ 33.948195] [<ffffffff83028b8f>] __sk_free+0x4f/0x220 [ 33.953441] [<ffffffff83028d8b>] sk_free+0x2b/0x40 [ 33.958443] [<ffffffff836c78f9>] pppol2tp_release+0x239/0x2e0 [ 33.964386] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 33.969896] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 33.975179] [<ffffffff815782e3>] __fput+0x263/0x700 [ 33.980253] [<ffffffff81578805>] ____fput+0x15/0x20 [ 33.985328] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 33.991045] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 33.997334] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 34.003016] [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.009909] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 <f0> 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 34.036681] RIP [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 34.043185] RSP <ffff8801b51cfca0> [ 34.046778] CR2: 0000000000000080 [ 34.050284] ---[ end trace 1520ac902f7a6a51 ]--- [ 34.055029] Kernel panic - not syncing: Fatal exception [ 34.060770] Dumping ftrace buffer: [ 34.064292] (ftrace buffer empty) [ 34.067975] Kernel Offset: disabled [ 34.071576] Rebooting in 86400 seconds..