[....] 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[ 16.278130] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.724763] random: sshd: uninitialized urandom read (32 bytes read) [ 21.980227] random: sshd: uninitialized urandom read (32 bytes read) [ 22.516210] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.13' (ECDSA) to the list of known hosts. [ 28.114303] urandom_read: 1 callbacks suppressed [ 28.114306] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.333783] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.342173] IP: [] l2tp_session_free+0x11c/0x200 [ 28.348812] PGD 1c1157067 [ 28.351468] PUD 1bcfeb067 PMD 0 [ 28.354993] [ 28.356629] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.361109] Dumping ftrace buffer: [ 28.364633] (ftrace buffer empty) [ 28.368350] Modules linked in: [ 28.371697] CPU: 1 PID: 3789 Comm: syz-executor025 Not tainted 4.9.119-g9dc978d #75 [ 28.379597] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.389073] task: ffff8801b964c800 task.stack: ffff8801b8ad8000 [ 28.395119] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.404086] RSP: 0018:ffff8801b8adfca0 EFLAGS: 00010246 [ 28.409892] RAX: dffffc0000000000 RBX: ffff8801c9c63900 RCX: 0000000000000000 [ 28.417154] RDX: 1ffff10037285970 RSI: ffffffff836bf9a1 RDI: ffff8801b942cb80 [ 28.424597] RBP: ffff8801b8adfcc0 R08: ffff8801b964d0e8 R09: 0000000000000000 [ 28.431857] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b942ca00 [ 28.439116] R13: ffff8801c9c63908 R14: 0000000000000000 R15: ffffffff83015be0 [ 28.446394] FS: 00000000020a7880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 28.454784] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.460656] CR2: 0000000000000080 CR3: 00000001c6dae000 CR4: 00000000001606f0 [ 28.467916] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.475177] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.482436] Stack: [ 28.484694] ffff8801b8392a80 ffff8801c9c63900 ffff8801b8392e50 ffff8801b8392d58 [ 28.493112] ffff8801b8adfce8 ffffffff836c72b2 ffff8801b8392ec0 ffff8801b8392a80 [ 28.501524] ffffffff836c71e0 ffff8801b8adfd20 ffffffff830230f5 ffff8801b8392ec0 [ 28.509613] Call Trace: [ 28.512209] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.519154] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.525465] [] __sk_destruct+0x55/0x590 [ 28.531377] [] ? sock_release+0x1c0/0x1c0 [ 28.537165] [] sk_destruct+0x63/0x80 [ 28.542829] [] __sk_free+0x4f/0x220 [ 28.548292] [] sk_free+0x2b/0x40 [ 28.553303] [] pppol2tp_release+0x239/0x2e0 [ 28.559513] [] sock_release+0x96/0x1c0 [ 28.565039] [] sock_close+0x16/0x20 [ 28.570308] [] __fput+0x263/0x700 [ 28.575422] [] ____fput+0x15/0x20 [ 28.580516] [] task_work_run+0x10c/0x180 [ 28.586228] [] exit_to_usermode_loop+0xfc/0x120 [ 28.592733] [] do_syscall_64+0x364/0x490 [ 28.598440] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.605490] 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 [ 28.633765] RIP [] l2tp_session_free+0x11c/0x200 [ 28.640304] RSP [ 28.643917] CR2: 0000000000000080 [ 28.647529] ---[ end trace 6ff31a4351ccce95 ]--- [ 28.652294] Kernel panic - not syncing: Fatal exception [ 28.658442] Dumping ftrace buffer: [ 28.661985] (ftrace buffer empty) [ 28.665860] Kernel Offset: disabled [ 28.669479] Rebooting in 86400 seconds..