[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.108436] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.714323] random: sshd: uninitialized urandom read (32 bytes read) [ 19.037059] random: sshd: uninitialized urandom read (32 bytes read) [ 19.524123] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.61' (ECDSA) to the list of known hosts. [ 25.195017] urandom_read: 1 callbacks suppressed [ 25.195021] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.415892] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.424106] IP: [] l2tp_session_free+0x11c/0x200 [ 25.430537] PGD 1c828b067 [ 25.433214] PUD 1c8276067 PMD 0 [ 25.436753] [ 25.438387] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.442862] Dumping ftrace buffer: [ 25.446381] (ftrace buffer empty) [ 25.450066] Modules linked in: [ 25.453357] CPU: 1 PID: 3787 Comm: syz-executor589 Not tainted 4.9.119-g9dc978d #75 [ 25.461126] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.470461] task: ffff8801baf98000 task.stack: ffff8801b8d48000 [ 25.476495] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.485431] RSP: 0018:ffff8801b8d4fca0 EFLAGS: 00010246 [ 25.490853] RAX: dffffc0000000000 RBX: ffff8801ba28bb80 RCX: 0000000000000000 [ 25.498102] RDX: 1ffff10039696e60 RSI: ffffffff836bf9a1 RDI: ffff8801cb4b7300 [ 25.505346] RBP: ffff8801b8d4fcc0 R08: ffff8801baf988e8 R09: 0000000000000000 [ 25.512598] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb4b7180 [ 25.519846] R13: ffff8801ba28bb88 R14: 0000000000000000 R15: ffffffff83015be0 [ 25.527200] FS: 0000000000819880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.535404] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.541262] CR2: 0000000000000080 CR3: 00000001c8e49000 CR4: 00000000001606f0 [ 25.548510] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.555754] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.563006] Stack: [ 25.565128] ffff8801b8d28880 ffff8801ba28bb80 ffff8801b8d28c50 ffff8801b8d28b58 [ 25.573262] ffff8801b8d4fce8 ffffffff836c72b2 ffff8801b8d28cc0 ffff8801b8d28880 [ 25.581266] ffffffff836c71e0 ffff8801b8d4fd20 ffffffff830230f5 ffff8801b8d28cc0 [ 25.589280] Call Trace: [ 25.591846] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.598729] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.605164] [] __sk_destruct+0x55/0x590 [ 25.610783] [] ? sock_release+0x1c0/0x1c0 [ 25.616623] [] sk_destruct+0x63/0x80 [ 25.622090] [] __sk_free+0x4f/0x220 [ 25.627344] [] sk_free+0x2b/0x40 [ 25.632470] [] pppol2tp_release+0x239/0x2e0 [ 25.638431] [] sock_release+0x96/0x1c0 [ 25.643945] [] sock_close+0x16/0x20 [ 25.649198] [] __fput+0x263/0x700 [ 25.654280] [] ____fput+0x15/0x20 [ 25.659364] [] task_work_run+0x10c/0x180 [ 25.665060] [] exit_to_usermode_loop+0xfc/0x120 [ 25.671457] [] do_syscall_64+0x364/0x490 [ 25.677151] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.684055] 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 [ 25.710977] RIP [] l2tp_session_free+0x11c/0x200 [ 25.717489] RSP [ 25.721093] CR2: 0000000000000080 [ 25.724895] ---[ end trace c95c60525a7b4535 ]--- [ 25.729668] Kernel panic - not syncing: Fatal exception [ 25.735389] Dumping ftrace buffer: [ 25.738910] (ftrace buffer empty) [ 25.742595] Kernel Offset: disabled [ 25.746201] Rebooting in 86400 seconds..