[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.425239] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.037628] random: sshd: uninitialized urandom read (32 bytes read) [ 15.269150] random: sshd: uninitialized urandom read (32 bytes read) [ 15.753313] random: sshd: uninitialized urandom read (32 bytes read) [ 34.886462] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.7' (ECDSA) to the list of known hosts. [ 40.275211] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 40.472149] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 40.480414] IP: [] l2tp_session_free+0x11c/0x200 [ 40.486836] PGD 1cacc6067 [ 40.489478] PUD 1c610a067 PMD 0 [ 40.492976] [ 40.494597] Oops: 0002 [#1] PREEMPT SMP KASAN [ 40.499078] Dumping ftrace buffer: [ 40.502593] (ftrace buffer empty) [ 40.506288] Modules linked in: [ 40.509579] CPU: 1 PID: 3811 Comm: syz-executor855 Not tainted 4.9.117-g8b21e85 #19 [ 40.517350] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.526692] task: ffff8801b7bf4800 task.stack: ffff8801d91a8000 [ 40.532897] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 40.541755] RSP: 0018:ffff8801d91afca0 EFLAGS: 00010246 [ 40.547179] RAX: dffffc0000000000 RBX: ffff8801b5fd0f00 RCX: 0000000000000000 [ 40.554423] RDX: 1ffff10039343c30 RSI: ffffffff836bf8f1 RDI: ffff8801c9a1e180 [ 40.561675] RBP: ffff8801d91afcc0 R08: ffff8801b7bf50e8 R09: 0000000000000000 [ 40.568919] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9a1e000 [ 40.576174] R13: ffff8801b5fd0f08 R14: 0000000000000000 R15: ffffffff83015be0 [ 40.583431] FS: 0000000001255880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 40.591641] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 40.597507] CR2: 0000000000000080 CR3: 00000001c845a000 CR4: 00000000001606f0 [ 40.604764] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 40.612017] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 40.619271] Stack: [ 40.621404] ffff8801d9160000 ffff8801b5fd0f00 ffff8801d91603d0 ffff8801d91602d8 [ 40.629411] ffff8801d91afce8 ffffffff836c7202 ffff8801d9160440 ffff8801d9160000 [ 40.637421] ffffffff836c7130 ffff8801d91afd20 ffffffff83023095 ffff8801d9160440 [ 40.645418] Call Trace: [ 40.647979] [] pppol2tp_session_destruct+0xd2/0x110 [ 40.654629] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 40.660932] [] __sk_destruct+0x55/0x590 [ 40.666531] [] ? sock_release+0x1c0/0x1c0 [ 40.672312] [] sk_destruct+0x63/0x80 [ 40.677653] [] __sk_free+0x4f/0x220 [ 40.682902] [] sk_free+0x2b/0x40 [ 40.687892] [] pppol2tp_release+0x239/0x2e0 [ 40.693836] [] sock_release+0x96/0x1c0 [ 40.699360] [] sock_close+0x16/0x20 [ 40.704624] [] __fput+0x263/0x700 [ 40.709701] [] ____fput+0x15/0x20 [ 40.714789] [] task_work_run+0x10c/0x180 [ 40.720477] [] exit_to_usermode_loop+0xfc/0x120 [ 40.726781] [] do_syscall_64+0x364/0x490 [ 40.732466] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 40.739373] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 40.766401] RIP [] l2tp_session_free+0x11c/0x200 [ 40.772915] RSP [ 40.776512] CR2: 0000000000000080 [ 40.780024] ---[ end trace d92be5453932ceff ]--- [ 40.784785] Kernel panic - not syncing: Fatal exception [ 40.790460] Dumping ftrace buffer: [ 40.793975] (ftrace buffer empty) [ 40.797668] Kernel Offset: disabled [ 40.801275] Rebooting in 86400 seconds..