[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.333686] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.651521] random: sshd: uninitialized urandom read (32 bytes read) [ 13.833870] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.634798] random: sshd: uninitialized urandom read (32 bytes read) [ 14.775149] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.40' (ECDSA) to the list of known hosts. [ 20.389118] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.584962] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 20.593233] IP: [] l2tp_session_free+0x11c/0x200 [ 20.599664] PGD 1c4daf067 [ 20.602307] PUD 1bf464067 PMD 0 [ 20.605784] [ 20.607406] Oops: 0002 [#1] PREEMPT SMP KASAN [ 20.611881] Dumping ftrace buffer: [ 20.615393] (ftrace buffer empty) [ 20.619082] Modules linked in: [ 20.622376] CPU: 1 PID: 3788 Comm: syz-executor637 Not tainted 4.9.117-g8b21e85 #71 [ 20.630142] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.639491] task: ffff8801b9b49800 task.stack: ffff8801b7500000 [ 20.645527] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 20.654420] RSP: 0018:ffff8801b7507ca0 EFLAGS: 00010246 [ 20.659845] RAX: dffffc0000000000 RBX: ffff8801c9a1f400 RCX: 0000000000000000 [ 20.667094] RDX: 1ffff10036feec80 RSI: ffffffff836bf8f1 RDI: ffff8801b7f76400 [ 20.674341] RBP: ffff8801b7507cc0 R08: ffff8801b9b4a0e8 R09: 0000000000000000 [ 20.681597] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7f76280 [ 20.688863] R13: ffff8801c9a1f408 R14: 0000000000000000 R15: ffffffff83015be0 [ 20.696132] FS: 00000000014ca880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 20.704369] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.710493] CR2: 0000000000000080 CR3: 00000001cd6a1000 CR4: 00000000001606f0 [ 20.717765] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 20.725011] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 20.732258] Stack: [ 20.734383] ffff8801b74ee600 ffff8801c9a1f400 ffff8801b74ee9d0 ffff8801b74ee8d8 [ 20.742394] ffff8801b7507ce8 ffffffff836c7202 ffff8801b74eea40 ffff8801b74ee600 [ 20.750386] ffffffff836c7130 ffff8801b7507d20 ffffffff83023095 ffff8801b74eea40 [ 20.758391] Call Trace: [ 20.760969] [] pppol2tp_session_destruct+0xd2/0x110 [ 20.767618] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 20.773913] [] __sk_destruct+0x55/0x590 [ 20.779522] [] ? sock_release+0x1c0/0x1c0 [ 20.785302] [] sk_destruct+0x63/0x80 [ 20.790647] [] __sk_free+0x4f/0x220 [ 20.795905] [] sk_free+0x2b/0x40 [ 20.800900] [] pppol2tp_release+0x239/0x2e0 [ 20.806847] [] sock_release+0x96/0x1c0 [ 20.812362] [] sock_close+0x16/0x20 [ 20.817637] [] __fput+0x263/0x700 [ 20.822721] [] ____fput+0x15/0x20 [ 20.827804] [] task_work_run+0x10c/0x180 [ 20.833490] [] exit_to_usermode_loop+0xfc/0x120 [ 20.839787] [] do_syscall_64+0x364/0x490 [ 20.845477] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 20.852383] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 20.879460] RIP [] l2tp_session_free+0x11c/0x200 [ 20.885967] RSP [ 20.889579] CR2: 0000000000000080 [ 20.893568] ---[ end trace 67e4b00f8a28963e ]--- [ 20.898366] Kernel panic - not syncing: Fatal exception [ 20.904078] Dumping ftrace buffer: [ 20.907611] (ftrace buffer empty) [ 20.911295] Kernel Offset: disabled [ 20.914895] Rebooting in 86400 seconds..