[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 17.103402] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 17.728756] random: sshd: uninitialized urandom read (32 bytes read) [ 17.988524] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.504283] random: sshd: uninitialized urandom read (32 bytes read) [ 33.878016] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.23' (ECDSA) to the list of known hosts. [ 39.313939] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 39.564184] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 39.573695] IP: [] l2tp_session_free+0x11c/0x200 [ 39.581752] PGD 1c7540067 [ 39.584615] PUD 1c81dc067 PMD 0 [ 39.590372] [ 39.592896] Oops: 0002 [#1] PREEMPT SMP KASAN [ 39.597508] Dumping ftrace buffer: [ 39.601046] (ftrace buffer empty) [ 39.604935] Modules linked in: [ 39.608265] CPU: 0 PID: 3809 Comm: syz-executor000 Not tainted 4.9.119-g9dc978d #75 [ 39.618188] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.629637] task: ffff8801b9fa1800 task.stack: ffff8801d9120000 [ 39.635911] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 39.646668] RSP: 0018:ffff8801d9127ca0 EFLAGS: 00010246 [ 39.652768] RAX: dffffc0000000000 RBX: ffff8801b8f49400 RCX: 0000000000000000 [ 39.661088] RDX: 1ffff10039687c30 RSI: ffffffff836bf9a1 RDI: ffff8801cb43e180 [ 39.668511] RBP: ffff8801d9127cc0 R08: ffff8801b9fa20e8 R09: 0000000000000000 [ 39.675778] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb43e000 [ 39.683039] R13: ffff8801b8f49408 R14: 0000000000000000 R15: ffffffff83015be0 [ 39.690607] FS: 0000000000c5b880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 39.699083] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 39.705071] CR2: 0000000000000080 CR3: 00000001c624d000 CR4: 00000000001606f0 [ 39.712528] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 39.719958] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 39.727247] Stack: [ 39.729567] ffff8801c7796600 ffff8801b8f49400 ffff8801c77969d0 ffff8801c77968d8 [ 39.738051] ffff8801d9127ce8 ffffffff836c72b2 ffff8801c7796a40 ffff8801c7796600 [ 39.746548] ffffffff836c71e0 ffff8801d9127d20 ffffffff830230f5 ffff8801c7796a40 [ 39.755121] Call Trace: [ 39.757997] [] pppol2tp_session_destruct+0xd2/0x110 [ 39.764656] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 39.771518] [] __sk_destruct+0x55/0x590 [ 39.777146] [] ? sock_release+0x1c0/0x1c0 [ 39.782934] [] sk_destruct+0x63/0x80 [ 39.788458] [] __sk_free+0x4f/0x220 [ 39.793865] [] sk_free+0x2b/0x40 [ 39.798871] [] pppol2tp_release+0x239/0x2e0 [ 39.805040] [] sock_release+0x96/0x1c0 [ 39.810740] [] sock_close+0x16/0x20 [ 39.816020] [] __fput+0x263/0x700 [ 39.822175] [] ____fput+0x15/0x20 [ 39.827678] [] task_work_run+0x10c/0x180 [ 39.833387] [] exit_to_usermode_loop+0xfc/0x120 [ 39.839882] [] do_syscall_64+0x364/0x490 [ 39.846155] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 39.853159] 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 f0 c9 fd 4c 89 ea 48 b8 00 [ 39.881906] RIP [] l2tp_session_free+0x11c/0x200 [ 39.888712] RSP [ 39.892513] CR2: 0000000000000080 [ 39.896777] ---[ end trace b0524b36da9f7abf ]--- [ 39.901711] Kernel panic - not syncing: Fatal exception [ 39.908282] Dumping ftrace buffer: [ 39.911915] (ftrace buffer empty) [ 39.915788] Kernel Offset: disabled [ 39.919411] Rebooting in 86400 seconds..