[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.620935] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.832718] random: sshd: uninitialized urandom read (32 bytes read) [ 19.106317] random: sshd: uninitialized urandom read (32 bytes read) [ 20.044002] random: sshd: uninitialized urandom read (32 bytes read) [ 32.280318] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.35' (ECDSA) to the list of known hosts. [ 37.703236] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 37.927643] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 37.935889] IP: [] l2tp_session_free+0x11c/0x200 [ 37.942311] PGD 1d90e8067 [ 37.944952] PUD 1d90ed067 PMD 0 [ 37.948426] [ 37.950045] Oops: 0002 [#1] PREEMPT SMP KASAN [ 37.954514] Dumping ftrace buffer: [ 37.958034] (ftrace buffer empty) [ 37.961728] Modules linked in: [ 37.965034] CPU: 1 PID: 3805 Comm: syz-executor997 Not tainted 4.9.113-g47bbcd6 #10 [ 37.972805] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.982155] task: ffff8801d8a00000 task.stack: ffff8801d8a40000 [ 37.988197] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 37.997077] RSP: 0018:ffff8801d8a47ca0 EFLAGS: 00010246 [ 38.002508] RAX: dffffc0000000000 RBX: ffff8801c6002f00 RCX: 0000000000000000 [ 38.009752] RDX: 1ffff10036d0da10 RSI: ffffffff836bcce1 RDI: ffff8801b686d080 [ 38.016997] RBP: ffff8801d8a47cc0 R08: ffff8801d8a008e8 R09: 0000000000000000 [ 38.024244] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b686cf00 [ 38.031488] R13: ffff8801c6002f08 R14: 0000000000000000 R15: ffffffff83013be0 [ 38.038745] FS: 000000000252d880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 38.046941] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 38.052806] CR2: 0000000000000080 CR3: 00000001d8c29000 CR4: 00000000001606f0 [ 38.060059] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 38.067313] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 38.074553] Stack: [ 38.076677] ffff8801d91f5d80 ffff8801c6002f00 ffff8801d91f6150 ffff8801d91f6058 [ 38.084657] ffff8801d8a47ce8 ffffffff836c45f2 ffff8801d91f61c0 ffff8801d91f5d80 [ 38.092661] ffffffff836c4520 ffff8801d8a47d20 ffffffff83021095 ffff8801d91f61c0 [ 38.100657] Call Trace: [ 38.103227] [] pppol2tp_session_destruct+0xd2/0x110 [ 38.109867] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 38.116158] [] __sk_destruct+0x55/0x590 [ 38.121755] [] ? sock_release+0x1c0/0x1c0 [ 38.127522] [] sk_destruct+0x63/0x80 [ 38.132856] [] __sk_free+0x4f/0x220 [ 38.138117] [] sk_free+0x2b/0x40 [ 38.143108] [] pppol2tp_release+0x239/0x2e0 [ 38.149049] [] sock_release+0x96/0x1c0 [ 38.154573] [] sock_close+0x16/0x20 [ 38.159823] [] __fput+0x263/0x700 [ 38.164898] [] ____fput+0x15/0x20 [ 38.169992] [] task_work_run+0x10c/0x180 [ 38.175677] [] exit_to_usermode_loop+0xfc/0x120 [ 38.181966] [] do_syscall_64+0x364/0x490 [ 38.187651] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 38.194546] 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 [ 38.221504] RIP [] l2tp_session_free+0x11c/0x200 [ 38.228023] RSP [ 38.231619] CR2: 0000000000000080 [ 38.235459] ---[ end trace 517624d6e3e88920 ]--- [ 38.240212] Kernel panic - not syncing: Fatal exception [ 38.245953] Dumping ftrace buffer: [ 38.249487] (ftrace buffer empty) [ 38.253174] Kernel Offset: disabled [ 38.256777] Rebooting in 86400 seconds..