[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.540131] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.373676] random: sshd: uninitialized urandom read (32 bytes read) [ 13.652597] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.490676] random: sshd: uninitialized urandom read (32 bytes read) [ 31.925571] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.55' (ECDSA) to the list of known hosts. [ 37.347912] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 37.555103] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 37.563390] IP: [] l2tp_session_free+0x11c/0x200 [ 37.569821] PGD 1c6d1b067 [ 37.572460] PUD 1c829d067 PMD 0 [ 37.575953] [ 37.577576] Oops: 0002 [#1] PREEMPT SMP KASAN [ 37.582054] Dumping ftrace buffer: [ 37.585574] (ftrace buffer empty) [ 37.589254] Modules linked in: [ 37.592533] CPU: 0 PID: 3813 Comm: syz-executor618 Not tainted 4.9.118-g47b77b8 #72 [ 37.600312] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.609639] task: ffff8801b6dcb000 task.stack: ffff8801d9268000 [ 37.615667] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 37.624513] RSP: 0018:ffff8801d926fca0 EFLAGS: 00010246 [ 37.629933] RAX: dffffc0000000000 RBX: ffff8801c8365180 RCX: 0000000000000000 [ 37.637194] RDX: 1ffff10039058c80 RSI: ffffffff836bf781 RDI: ffff8801c82c6400 [ 37.644434] RBP: ffff8801d926fcc0 R08: ffff8801b6dcb8e8 R09: 0000000000000000 [ 37.651675] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c82c6280 [ 37.659392] R13: ffff8801c8365188 R14: 0000000000000000 R15: ffffffff83015be0 [ 37.667159] FS: 0000000001cb6880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 37.675371] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 37.681231] CR2: 0000000000000080 CR3: 00000001c6d2d000 CR4: 00000000001606f0 [ 37.688476] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 37.695905] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 37.703145] Stack: [ 37.705268] ffff8801b5f55d80 ffff8801c8365180 ffff8801b5f56150 ffff8801b5f56058 [ 37.713251] ffff8801d926fce8 ffffffff836c7092 ffff8801b5f561c0 ffff8801b5f55d80 [ 37.721237] ffffffff836c6fc0 ffff8801d926fd20 ffffffff830230f5 ffff8801b5f561c0 [ 37.729251] Call Trace: [ 37.731821] [] pppol2tp_session_destruct+0xd2/0x110 [ 37.738459] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 37.744752] [] __sk_destruct+0x55/0x590 [ 37.750360] [] ? sock_release+0x1c0/0x1c0 [ 37.756128] [] sk_destruct+0x63/0x80 [ 37.761469] [] __sk_free+0x4f/0x220 [ 37.766733] [] sk_free+0x2b/0x40 [ 37.771720] [] pppol2tp_release+0x239/0x2e0 [ 37.777661] [] sock_release+0x96/0x1c0 [ 37.783183] [] sock_close+0x16/0x20 [ 37.788433] [] __fput+0x263/0x700 [ 37.793523] [] ____fput+0x15/0x20 [ 37.798619] [] task_work_run+0x10c/0x180 [ 37.804303] [] exit_to_usermode_loop+0xfc/0x120 [ 37.810591] [] do_syscall_64+0x364/0x490 [ 37.816273] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.823165] 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 f5 f2 c9 fd 4c 89 ea 48 b8 00 [ 37.850119] RIP [] l2tp_session_free+0x11c/0x200 [ 37.856627] RSP [ 37.860227] CR2: 0000000000000080 [ 37.863816] ---[ end trace 0be05ce8e562d8ab ]--- [ 37.868571] Kernel panic - not syncing: Fatal exception [ 37.874220] Dumping ftrace buffer: [ 37.877733] (ftrace buffer empty) [ 37.881420] Kernel Offset: disabled [ 37.885020] Rebooting in 86400 seconds..