[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.858000] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.546136] random: sshd: uninitialized urandom read (32 bytes read) [ 16.692625] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.207133] random: sshd: uninitialized urandom read (32 bytes read) [ 29.059832] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.62' (ECDSA) to the list of known hosts. [ 34.552381] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.760521] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.768925] IP: [] l2tp_session_free+0x11c/0x200 [ 34.775342] PGD 1c4ed8067 [ 34.777985] PUD 1bd300067 PMD 0 [ 34.781464] [ 34.783085] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.787555] Dumping ftrace buffer: [ 34.791064] (ftrace buffer empty) [ 34.794749] Modules linked in: [ 34.798039] CPU: 0 PID: 3800 Comm: syz-executor850 Not tainted 4.9.122-g54068d6 #26 [ 34.805825] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.815247] task: ffff8801b8388000 task.stack: ffff8801da3a0000 [ 34.821285] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.830153] RSP: 0018:ffff8801da3a7ca0 EFLAGS: 00010246 [ 34.835575] RAX: dffffc0000000000 RBX: ffff8801cb3e4f00 RCX: 0000000000000000 [ 34.842925] RDX: 1ffff10036fda700 RSI: ffffffff836c39a1 RDI: ffff8801b7ed3800 [ 34.850184] RBP: ffff8801da3a7cc0 R08: ffff8801b83888e8 R09: 0000000000000000 [ 34.857435] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7ed3680 [ 34.864682] R13: ffff8801cb3e4f08 R14: 0000000000000000 R15: ffffffff83019be0 [ 34.871933] FS: 0000000001890880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.880137] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.885992] CR2: 0000000000000080 CR3: 00000001b65d1000 CR4: 00000000001606f0 [ 34.893322] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.900573] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.907819] Stack: [ 34.909949] ffff8801b6a36e80 ffff8801cb3e4f00 ffff8801b6a37250 ffff8801b6a37158 [ 34.918090] ffff8801da3a7ce8 ffffffff836cb2b2 ffff8801b6a372c0 ffff8801b6a36e80 [ 34.926100] ffffffff836cb1e0 ffff8801da3a7d20 ffffffff830270f5 ffff8801b6a372c0 [ 34.934155] Call Trace: [ 34.936726] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.943378] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.949676] [] __sk_destruct+0x55/0x590 [ 34.955389] [] ? sock_release+0x1c0/0x1c0 [ 34.961176] [] sk_destruct+0x63/0x80 [ 34.966514] [] __sk_free+0x4f/0x220 [ 34.971772] [] sk_free+0x2b/0x40 [ 34.976775] [] pppol2tp_release+0x239/0x2e0 [ 34.982729] [] sock_release+0x96/0x1c0 [ 34.988242] [] sock_close+0x16/0x20 [ 34.993501] [] __fput+0x263/0x700 [ 34.998590] [] ____fput+0x15/0x20 [ 35.003670] [] task_work_run+0x10c/0x180 [ 35.009359] [] exit_to_usermode_loop+0xfc/0x120 [ 35.015655] [] do_syscall_64+0x364/0x490 [ 35.021345] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.028242] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 35.055331] RIP [] l2tp_session_free+0x11c/0x200 [ 35.061835] RSP [ 35.065440] CR2: 0000000000000080 [ 35.069167] ---[ end trace d9050682d6d34f64 ]--- [ 35.073929] Kernel panic - not syncing: Fatal exception [ 35.079701] Dumping ftrace buffer: [ 35.083216] (ftrace buffer empty) [ 35.086902] Kernel Offset: disabled [ 35.090504] Rebooting in 86400 seconds..