[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.903590] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.817439] random: sshd: uninitialized urandom read (32 bytes read) [ 26.418124] random: sshd: uninitialized urandom read (32 bytes read) [ 26.843385] random: sshd: uninitialized urandom read (32 bytes read) [ 30.393928] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.43' (ECDSA) to the list of known hosts. [ 35.840152] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 36.075206] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 36.083459] IP: [] l2tp_session_free+0x11c/0x200 [ 36.089895] PGD 1c9c3d067 [ 36.092537] PUD 1c92fe067 PMD 0 [ 36.096030] [ 36.097654] Oops: 0002 [#1] PREEMPT SMP KASAN [ 36.102126] Dumping ftrace buffer: [ 36.105642] (ftrace buffer empty) [ 36.109329] Modules linked in: [ 36.112620] CPU: 1 PID: 3811 Comm: syz-executor524 Not tainted 4.9.117-g8b21e85 #71 [ 36.120387] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.129767] task: ffff8801b5c2e000 task.stack: ffff8801d9578000 [ 36.135828] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 36.144689] RSP: 0018:ffff8801d957fca0 EFLAGS: 00010246 [ 36.150115] RAX: dffffc0000000000 RBX: ffff8801c901d900 RCX: 0000000000000000 [ 36.157375] RDX: 1ffff100392428d0 RSI: ffffffff836bf8f1 RDI: ffff8801c9214680 [ 36.164631] RBP: ffff8801d957fcc0 R08: ffff8801b5c2e8e8 R09: 0000000000000000 [ 36.171886] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9214500 [ 36.179133] R13: ffff8801c901d908 R14: 0000000000000000 R15: ffffffff83015be0 [ 36.186402] FS: 0000000000c93880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 36.194616] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.200483] CR2: 0000000000000080 CR3: 00000001cb0a8000 CR4: 00000000001606f0 [ 36.207741] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 36.214990] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 36.222235] Stack: [ 36.224363] ffff8801b5ac8000 ffff8801c901d900 ffff8801b5ac83d0 ffff8801b5ac82d8 [ 36.232368] ffff8801d957fce8 ffffffff836c7202 ffff8801b5ac8440 ffff8801b5ac8000 [ 36.240368] ffffffff836c7130 ffff8801d957fd20 ffffffff83023095 ffff8801b5ac8440 [ 36.248382] Call Trace: [ 36.250955] [] pppol2tp_session_destruct+0xd2/0x110 [ 36.257608] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 36.263903] [] __sk_destruct+0x55/0x590 [ 36.269519] [] ? sock_release+0x1c0/0x1c0 [ 36.275304] [] sk_destruct+0x63/0x80 [ 36.280649] [] __sk_free+0x4f/0x220 [ 36.285899] [] sk_free+0x2b/0x40 [ 36.290891] [] pppol2tp_release+0x239/0x2e0 [ 36.296837] [] sock_release+0x96/0x1c0 [ 36.302352] [] sock_close+0x16/0x20 [ 36.307607] [] __fput+0x263/0x700 [ 36.312686] [] ____fput+0x15/0x20 [ 36.317767] [] task_work_run+0x10c/0x180 [ 36.323467] [] exit_to_usermode_loop+0xfc/0x120 [ 36.329762] [] do_syscall_64+0x364/0x490 [ 36.335721] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 36.342626] 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 [ 36.369679] RIP [] l2tp_session_free+0x11c/0x200 [ 36.376182] RSP [ 36.379780] CR2: 0000000000000080 [ 36.384043] ---[ end trace e96347f27d559533 ]--- [ 36.388870] Kernel panic - not syncing: Fatal exception [ 36.394577] Dumping ftrace buffer: [ 36.398100] (ftrace buffer empty) [ 36.401788] Kernel Offset: disabled [ 36.405399] Rebooting in 86400 seconds..