[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.841549] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.852045] random: sshd: uninitialized urandom read (32 bytes read) [ 16.266302] random: sshd: uninitialized urandom read (32 bytes read) [ 17.113264] random: sshd: uninitialized urandom read (32 bytes read) [ 22.393236] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.29' (ECDSA) to the list of known hosts. [ 27.823275] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.020078] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.028367] IP: [] l2tp_session_free+0x11c/0x200 [ 28.034828] PGD 1c83e7067 [ 28.037474] PUD 1c83ed067 PMD 0 [ 28.040957] [ 28.042580] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.047064] Dumping ftrace buffer: [ 28.050579] (ftrace buffer empty) [ 28.054266] Modules linked in: [ 28.057553] CPU: 1 PID: 3799 Comm: syz-executor494 Not tainted 4.9.116-g52be322 #69 [ 28.065329] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.074665] task: ffff8801b8868000 task.stack: ffff8801b6730000 [ 28.080707] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.089600] RSP: 0018:ffff8801b6737ca0 EFLAGS: 00010246 [ 28.095028] RAX: dffffc0000000000 RBX: ffff8801ca2e6f00 RCX: 0000000000000000 [ 28.102284] RDX: 1ffff100371a6480 RSI: ffffffff836be8f1 RDI: ffff8801b8d32400 [ 28.109557] RBP: ffff8801b6737cc0 R08: ffff8801b88688e8 R09: 0000000000000000 [ 28.116809] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b8d32280 [ 28.124077] R13: ffff8801ca2e6f08 R14: 0000000000000000 R15: ffffffff83014be0 [ 28.131339] FS: 0000000001aa6880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 28.139552] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.145419] CR2: 0000000000000080 CR3: 00000001c8204000 CR4: 00000000001606f0 [ 28.152687] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.159935] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.167201] Stack: [ 28.169338] ffff8801bd315d80 ffff8801ca2e6f00 ffff8801bd316150 ffff8801bd316058 [ 28.177344] ffff8801b6737ce8 ffffffff836c6202 ffff8801bd3161c0 ffff8801bd315d80 [ 28.185372] ffffffff836c6130 ffff8801b6737d20 ffffffff83022095 ffff8801bd3161c0 [ 28.193392] Call Trace: [ 28.195963] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.202706] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.209012] [] __sk_destruct+0x55/0x590 [ 28.214617] [] ? sock_release+0x1c0/0x1c0 [ 28.220396] [] sk_destruct+0x63/0x80 [ 28.225738] [] __sk_free+0x4f/0x220 [ 28.231000] [] sk_free+0x2b/0x40 [ 28.235995] [] pppol2tp_release+0x239/0x2e0 [ 28.241943] [] sock_release+0x96/0x1c0 [ 28.247460] [] sock_close+0x16/0x20 [ 28.252713] [] __fput+0x263/0x700 [ 28.257791] [] ____fput+0x15/0x20 [ 28.262873] [] task_work_run+0x10c/0x180 [ 28.268571] [] exit_to_usermode_loop+0xfc/0x120 [ 28.274872] [] do_syscall_64+0x364/0x490 [ 28.280569] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.287467] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 28.314513] RIP [] l2tp_session_free+0x11c/0x200 [ 28.321023] RSP [ 28.324622] CR2: 0000000000000080 [ 28.328140] ---[ end trace 6afc58713a88027d ]--- [ 28.332906] Kernel panic - not syncing: Fatal exception [ 28.338717] Dumping ftrace buffer: [ 28.342237] (ftrace buffer empty) [ 28.345920] Kernel Offset: disabled [ 28.349552] Rebooting in 86400 seconds..