[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.198088] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.402714] random: sshd: uninitialized urandom read (32 bytes read) [ 18.665331] random: sshd: uninitialized urandom read (32 bytes read) [ 19.784136] random: sshd: uninitialized urandom read (32 bytes read) [ 19.917606] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.27' (ECDSA) to the list of known hosts. [ 25.307406] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.519851] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.528198] IP: [] l2tp_session_free+0x11c/0x200 [ 25.534630] PGD 1c088f067 [ 25.537269] PUD 1c0bbd067 PMD 0 [ 25.540839] [ 25.542464] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.546957] Dumping ftrace buffer: [ 25.550485] (ftrace buffer empty) [ 25.554194] Modules linked in: [ 25.557479] CPU: 1 PID: 3799 Comm: syz-executor486 Not tainted 4.9.116-g0137ea2 #70 [ 25.565265] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.574595] task: ffff8801b7d74800 task.stack: ffff8801b6660000 [ 25.580625] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.589480] RSP: 0018:ffff8801b6667ca0 EFLAGS: 00010246 [ 25.594902] RAX: dffffc0000000000 RBX: ffff8801b887e000 RCX: 0000000000000000 [ 25.602147] RDX: 1ffff1003965e970 RSI: ffffffff836be8f1 RDI: ffff8801cb2f4b80 [ 25.609393] RBP: ffff8801b6667cc0 R08: ffff8801b7d750e8 R09: 0000000000000000 [ 25.616647] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb2f4a00 [ 25.623907] R13: ffff8801b887e008 R14: 0000000000000000 R15: ffffffff83014be0 [ 25.631161] FS: 0000000000da9880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.639374] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.645232] CR2: 0000000000000080 CR3: 00000001c0975000 CR4: 00000000001606f0 [ 25.652476] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.659734] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.667001] Stack: [ 25.669136] ffff8801b6f7cc80 ffff8801b887e000 ffff8801b6f7d050 ffff8801b6f7cf58 [ 25.677137] ffff8801b6667ce8 ffffffff836c6202 ffff8801b6f7d0c0 ffff8801b6f7cc80 [ 25.685202] ffffffff836c6130 ffff8801b6667d20 ffffffff83022095 ffff8801b6f7d0c0 [ 25.693213] Call Trace: [ 25.695793] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.702431] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.708724] [] __sk_destruct+0x55/0x590 [ 25.714340] [] ? sock_release+0x1c0/0x1c0 [ 25.720118] [] sk_destruct+0x63/0x80 [ 25.725492] [] __sk_free+0x4f/0x220 [ 25.730759] [] sk_free+0x2b/0x40 [ 25.735757] [] pppol2tp_release+0x239/0x2e0 [ 25.741701] [] sock_release+0x96/0x1c0 [ 25.747213] [] sock_close+0x16/0x20 [ 25.752465] [] __fput+0x263/0x700 [ 25.757542] [] ____fput+0x15/0x20 [ 25.762626] [] task_work_run+0x10c/0x180 [ 25.768320] [] exit_to_usermode_loop+0xfc/0x120 [ 25.774619] [] do_syscall_64+0x364/0x490 [ 25.780316] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.787211] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 25.814361] RIP [] l2tp_session_free+0x11c/0x200 [ 25.820953] RSP [ 25.824554] CR2: 0000000000000080 [ 25.828187] ---[ end trace 2209bae66a295cb8 ]--- [ 25.832951] Kernel panic - not syncing: Fatal exception [ 25.838670] Dumping ftrace buffer: [ 25.842189] (ftrace buffer empty) [ 25.845873] Kernel Offset: disabled [ 25.849475] Rebooting in 86400 seconds..