[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.315954] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.269046] random: sshd: uninitialized urandom read (32 bytes read) [ 14.466755] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.951911] random: sshd: uninitialized urandom read (32 bytes read) [ 15.082537] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.38' (ECDSA) to the list of known hosts. [ 20.836592] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.037490] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.045708] IP: [] l2tp_session_free+0x11c/0x200 [ 21.052147] PGD 1c8be9067 [ 21.054789] PUD 1c7a32067 PMD 0 [ 21.058284] [ 21.059922] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.064388] Dumping ftrace buffer: [ 21.067900] (ftrace buffer empty) [ 21.071594] Modules linked in: [ 21.074884] CPU: 1 PID: 3792 Comm: syz-executor597 Not tainted 4.9.122-g54068d6 #26 [ 21.082664] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.092009] task: ffff8801b888e000 task.stack: ffff8801b7198000 [ 21.098046] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.106899] RSP: 0018:ffff8801b719fca0 EFLAGS: 00010246 [ 21.112321] RAX: dffffc0000000000 RBX: ffff8801cb72b180 RCX: 0000000000000000 [ 21.119565] RDX: 1ffff10036f3fc30 RSI: ffffffff836c39a1 RDI: ffff8801b79fe180 [ 21.126815] RBP: ffff8801b719fcc0 R08: ffff8801b888e8e8 R09: 0000000000000000 [ 21.134073] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b79fe000 [ 21.141329] R13: ffff8801cb72b188 R14: 0000000000000000 R15: ffffffff83019be0 [ 21.148578] FS: 00000000022a9880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.156784] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.162654] CR2: 0000000000000080 CR3: 00000001c4d23000 CR4: 00000000001606f0 [ 21.169903] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.177148] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.184390] Stack: [ 21.186527] ffff8801b6eab300 ffff8801cb72b180 ffff8801b6eab6d0 ffff8801b6eab5d8 [ 21.194550] ffff8801b719fce8 ffffffff836cb2b2 ffff8801b6eab740 ffff8801b6eab300 [ 21.202576] ffffffff836cb1e0 ffff8801b719fd20 ffffffff830270f5 ffff8801b6eab740 [ 21.210605] Call Trace: [ 21.213179] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.219824] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.226118] [] __sk_destruct+0x55/0x590 [ 21.231726] [] ? sock_release+0x1c0/0x1c0 [ 21.237506] [] sk_destruct+0x63/0x80 [ 21.242846] [] __sk_free+0x4f/0x220 [ 21.248099] [] sk_free+0x2b/0x40 [ 21.253090] [] pppol2tp_release+0x239/0x2e0 [ 21.259038] [] sock_release+0x96/0x1c0 [ 21.264551] [] sock_close+0x16/0x20 [ 21.269808] [] __fput+0x263/0x700 [ 21.274888] [] ____fput+0x15/0x20 [ 21.279967] [] task_work_run+0x10c/0x180 [ 21.285674] [] exit_to_usermode_loop+0xfc/0x120 [ 21.291977] [] do_syscall_64+0x364/0x490 [ 21.297667] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.304565] 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 [ 21.331586] RIP [] l2tp_session_free+0x11c/0x200 [ 21.338109] RSP [ 21.341710] CR2: 0000000000000080 [ 21.345581] ---[ end trace 670ea21be08f2b0c ]--- [ 21.350359] Kernel panic - not syncing: Fatal exception [ 21.356076] Dumping ftrace buffer: [ 21.359596] (ftrace buffer empty) [ 21.363281] Kernel Offset: disabled [ 21.366879] Rebooting in 86400 seconds..