[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.015965] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.865849] random: sshd: uninitialized urandom read (32 bytes read) [ 19.212821] random: sshd: uninitialized urandom read (32 bytes read) [ 20.151438] random: sshd: uninitialized urandom read (32 bytes read) [ 20.293763] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.1' (ECDSA) to the list of known hosts. [ 25.686027] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.882100] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.890335] IP: [] l2tp_session_free+0x11c/0x200 [ 25.896778] PGD 1c82be067 [ 25.899419] PUD 1c8183067 PMD 0 [ 25.902897] [ 25.904514] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.908987] Dumping ftrace buffer: [ 25.912497] (ftrace buffer empty) [ 25.916179] Modules linked in: [ 25.919462] CPU: 0 PID: 3799 Comm: syz-executor442 Not tainted 4.9.113-g47bbcd6 #10 [ 25.927232] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.936571] task: ffff8801b8aab000 task.stack: ffff8801b5f40000 [ 25.942598] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.951466] RSP: 0018:ffff8801b5f47ca0 EFLAGS: 00010246 [ 25.956888] RAX: dffffc0000000000 RBX: ffff8801b6276c80 RCX: 0000000000000000 [ 25.964132] RDX: 1ffff10036fb4350 RSI: ffffffff836bcce1 RDI: ffff8801b7da1a80 [ 25.971470] RBP: ffff8801b5f47cc0 R08: ffff8801b8aab8e8 R09: 0000000000000000 [ 25.978723] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7da1900 [ 25.985974] R13: ffff8801b6276c88 R14: 0000000000000000 R15: ffffffff83013be0 [ 25.993218] FS: 000000000122d880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 26.001423] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.007281] CR2: 0000000000000080 CR3: 00000001c9187000 CR4: 00000000001606f0 [ 26.014526] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.021772] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.029017] Stack: [ 26.031139] ffff8801d90ab300 ffff8801b6276c80 ffff8801d90ab6d0 ffff8801d90ab5d8 [ 26.039129] ffff8801b5f47ce8 ffffffff836c45f2 ffff8801d90ab740 ffff8801d90ab300 [ 26.047114] ffffffff836c4520 ffff8801b5f47d20 ffffffff83021095 ffff8801d90ab740 [ 26.055094] Call Trace: [ 26.057656] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.064301] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.070602] [] __sk_destruct+0x55/0x590 [ 26.076213] [] ? sock_release+0x1c0/0x1c0 [ 26.081990] [] sk_destruct+0x63/0x80 [ 26.087333] [] __sk_free+0x4f/0x220 [ 26.092583] [] sk_free+0x2b/0x40 [ 26.097575] [] pppol2tp_release+0x239/0x2e0 [ 26.103527] [] sock_release+0x96/0x1c0 [ 26.109036] [] sock_close+0x16/0x20 [ 26.114286] [] __fput+0x263/0x700 [ 26.119365] [] ____fput+0x15/0x20 [ 26.124447] [] task_work_run+0x10c/0x180 [ 26.130136] [] exit_to_usermode_loop+0xfc/0x120 [ 26.136432] [] do_syscall_64+0x364/0x490 [ 26.142118] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.149012] 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 [ 26.175827] RIP [] l2tp_session_free+0x11c/0x200 [ 26.182340] RSP [ 26.185937] CR2: 0000000000000080 [ 26.189457] ---[ end trace f39e63107f83f595 ]--- [ 26.194215] Kernel panic - not syncing: Fatal exception [ 26.200164] Dumping ftrace buffer: [ 26.203676] (ftrace buffer empty) [ 26.207358] Kernel Offset: disabled [ 26.210957] Rebooting in 86400 seconds..