[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.081409] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.119481] random: sshd: uninitialized urandom read (32 bytes read) [ 20.444034] random: sshd: uninitialized urandom read (32 bytes read) [ 20.936393] random: sshd: uninitialized urandom read (32 bytes read) [ 34.183473] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.13' (ECDSA) to the list of known hosts. [ 39.836222] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 40.024769] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 40.033160] IP: [] l2tp_session_free+0x11c/0x200 [ 40.039667] PGD 1be6a0067 [ 40.042323] PUD 1be6a1067 PMD 0 [ 40.045815] [ 40.047445] Oops: 0002 [#1] PREEMPT SMP KASAN [ 40.051921] Dumping ftrace buffer: [ 40.055578] (ftrace buffer empty) [ 40.059277] Modules linked in: [ 40.062583] CPU: 1 PID: 3798 Comm: syz-executor961 Not tainted 4.9.119-g9dc978d #75 [ 40.070354] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.079688] task: ffff8801badc6000 task.stack: ffff8801d9548000 [ 40.085724] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 40.094586] RSP: 0018:ffff8801d954fca0 EFLAGS: 00010246 [ 40.100016] RAX: dffffc0000000000 RBX: ffff8801c907ca00 RCX: 0000000000000000 [ 40.107292] RDX: 1ffff10037258480 RSI: ffffffff836bf9a1 RDI: ffff8801b92c2400 [ 40.114541] RBP: ffff8801d954fcc0 R08: ffff8801badc68e8 R09: 0000000000000000 [ 40.121798] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b92c2280 [ 40.129051] R13: ffff8801c907ca08 R14: 0000000000000000 R15: ffffffff83015be0 [ 40.136303] FS: 0000000000a33880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 40.144509] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 40.150373] CR2: 0000000000000080 CR3: 00000001be68d000 CR4: 00000000001606f0 [ 40.157655] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 40.164904] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 40.172159] Stack: [ 40.174290] ffff8801d91faa80 ffff8801c907ca00 ffff8801d91fae50 ffff8801d91fad58 [ 40.182310] ffff8801d954fce8 ffffffff836c72b2 ffff8801d91faec0 ffff8801d91faa80 [ 40.190339] ffffffff836c71e0 ffff8801d954fd20 ffffffff830230f5 ffff8801d91faec0 [ 40.198375] Call Trace: [ 40.200950] [] pppol2tp_session_destruct+0xd2/0x110 [ 40.207612] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 40.213916] [] __sk_destruct+0x55/0x590 [ 40.219522] [] ? sock_release+0x1c0/0x1c0 [ 40.225303] [] sk_destruct+0x63/0x80 [ 40.230644] [] __sk_free+0x4f/0x220 [ 40.235901] [] sk_free+0x2b/0x40 [ 40.240899] [] pppol2tp_release+0x239/0x2e0 [ 40.246850] [] sock_release+0x96/0x1c0 [ 40.252366] [] sock_close+0x16/0x20 [ 40.257624] [] __fput+0x263/0x700 [ 40.262707] [] ____fput+0x15/0x20 [ 40.267793] [] task_work_run+0x10c/0x180 [ 40.273485] [] exit_to_usermode_loop+0xfc/0x120 [ 40.279781] [] do_syscall_64+0x364/0x490 [ 40.285473] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 40.292377] 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 [ 40.319755] RIP [] l2tp_session_free+0x11c/0x200 [ 40.326269] RSP [ 40.329873] CR2: 0000000000000080 [ 40.333426] ---[ end trace 85ffa10d61d7c3e4 ]--- [ 40.338189] Kernel panic - not syncing: Fatal exception [ 40.344001] Dumping ftrace buffer: [ 40.347527] (ftrace buffer empty) [ 40.351217] Kernel Offset: disabled [ 40.354823] Rebooting in 86400 seconds..