[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.160111] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.390026] random: sshd: uninitialized urandom read (32 bytes read) [ 20.890640] random: sshd: uninitialized urandom read (32 bytes read) [ 21.880702] random: sshd: uninitialized urandom read (32 bytes read) [ 22.012576] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.31' (ECDSA) to the list of known hosts. [ 27.448129] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.635607] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.643834] IP: [] l2tp_session_free+0x11c/0x200 [ 27.650258] PGD 1c75c2067 [ 27.652906] PUD 1ca78e067 PMD 0 [ 27.656395] [ 27.658021] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.662487] Dumping ftrace buffer: [ 27.665997] (ftrace buffer empty) [ 27.669682] Modules linked in: [ 27.672979] CPU: 1 PID: 3798 Comm: syz-executor366 Not tainted 4.9.113-g47bbcd6 #62 [ 27.680744] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.690076] task: ffff8801b8d06000 task.stack: ffff8801b67e8000 [ 27.696115] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.704983] RSP: 0018:ffff8801b67efca0 EFLAGS: 00010246 [ 27.710406] RAX: dffffc0000000000 RBX: ffff8801c6405400 RCX: 0000000000000000 [ 27.717668] RDX: 1ffff10038c808d0 RSI: ffffffff836bcce1 RDI: ffff8801c6404680 [ 27.724914] RBP: ffff8801b67efcc0 R08: ffff8801b8d068e8 R09: 0000000000000000 [ 27.732186] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c6404500 [ 27.739441] R13: ffff8801c6405408 R14: 0000000000000000 R15: ffffffff83013be0 [ 27.746687] FS: 0000000001b18880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.754897] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.760756] CR2: 0000000000000080 CR3: 00000001c776e000 CR4: 00000000001606f0 [ 27.768010] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.775259] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.782502] Stack: [ 27.784647] ffff8801b7d95d80 ffff8801c6405400 ffff8801b7d96150 ffff8801b7d96058 [ 27.792644] ffff8801b67efce8 ffffffff836c45f2 ffff8801b7d961c0 ffff8801b7d95d80 [ 27.800644] ffffffff836c4520 ffff8801b67efd20 ffffffff83021095 ffff8801b7d961c0 [ 27.808810] Call Trace: [ 27.811375] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.818031] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.824334] [] __sk_destruct+0x55/0x590 [ 27.829942] [] ? sock_release+0x1c0/0x1c0 [ 27.835731] [] sk_destruct+0x63/0x80 [ 27.841078] [] __sk_free+0x4f/0x220 [ 27.846332] [] sk_free+0x2b/0x40 [ 27.851331] [] pppol2tp_release+0x239/0x2e0 [ 27.857283] [] sock_release+0x96/0x1c0 [ 27.862799] [] sock_close+0x16/0x20 [ 27.868067] [] __fput+0x263/0x700 [ 27.873161] [] ____fput+0x15/0x20 [ 27.878240] [] task_work_run+0x10c/0x180 [ 27.883926] [] exit_to_usermode_loop+0xfc/0x120 [ 27.890218] [] do_syscall_64+0x364/0x490 [ 27.895901] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.902793] 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 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 27.929710] RIP [] l2tp_session_free+0x11c/0x200 [ 27.936213] RSP [ 27.939827] CR2: 0000000000000080 [ 27.943339] ---[ end trace 52107ab8ecf39c44 ]--- [ 27.948094] Kernel panic - not syncing: Fatal exception [ 27.953909] Dumping ftrace buffer: [ 27.957435] (ftrace buffer empty) [ 27.961118] Kernel Offset: disabled [ 27.964718] Rebooting in 86400 seconds..