[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 11.988605] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.411013] random: sshd: uninitialized urandom read (32 bytes read) [ 16.826817] random: sshd: uninitialized urandom read (32 bytes read) [ 17.754861] random: sshd: uninitialized urandom read (32 bytes read) [ 25.874427] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.54' (ECDSA) to the list of known hosts. [ 31.308164] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 31.517839] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 31.526060] IP: [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 31.532473] PGD 1c040e067 [ 31.535110] PUD 1bb8ed067 PMD 0 [ 31.538585] [ 31.540204] Oops: 0002 [#1] PREEMPT SMP KASAN [ 31.544671] Dumping ftrace buffer: [ 31.548211] (ftrace buffer empty) [ 31.551892] Modules linked in: [ 31.555174] CPU: 1 PID: 3797 Comm: syz-executor593 Not tainted 4.9.113-g47bbcd6 #62 [ 31.562936] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.572264] task: ffff8801b9124800 task.stack: ffff8801b62f0000 [ 31.578288] RIP: 0010:[<ffffffff836bcd0c>] [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 31.587127] RSP: 0018:ffff8801b62f7ca0 EFLAGS: 00010246 [ 31.592543] RAX: dffffc0000000000 RBX: ffff8801c61d2a00 RCX: 0000000000000000 [ 31.599794] RDX: 1ffff10038c21660 RSI: ffffffff836bcce1 RDI: ffff8801c610b300 [ 31.607035] RBP: ffff8801b62f7cc0 R08: ffff8801b91250e8 R09: 0000000000000000 [ 31.614287] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c610b180 [ 31.621526] R13: ffff8801c61d2a08 R14: 0000000000000000 R15: ffffffff83013be0 [ 31.628769] FS: 0000000001b43880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 31.636964] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.642816] CR2: 0000000000000080 CR3: 00000001c04e5000 CR4: 00000000001606f0 [ 31.650056] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 31.657299] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 31.664539] Stack: [ 31.666666] ffff8801d9679100 ffff8801c61d2a00 ffff8801d96794d0 ffff8801d96793d8 [ 31.674642] ffff8801b62f7ce8 ffffffff836c45f2 ffff8801d9679540 ffff8801d9679100 [ 31.682612] ffffffff836c4520 ffff8801b62f7d20 ffffffff83021095 ffff8801d9679540 [ 31.690619] Call Trace: [ 31.693182] [<ffffffff836c45f2>] pppol2tp_session_destruct+0xd2/0x110 [ 31.699818] [<ffffffff836c4520>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.706108] [<ffffffff83021095>] __sk_destruct+0x55/0x590 [ 31.711703] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 31.717471] [<ffffffff83028b23>] sk_destruct+0x63/0x80 [ 31.722804] [<ffffffff83028b8f>] __sk_free+0x4f/0x220 [ 31.728062] [<ffffffff83028d8b>] sk_free+0x2b/0x40 [ 31.733046] [<ffffffff836c78f9>] pppol2tp_release+0x239/0x2e0 [ 31.738990] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 31.749706] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 31.754955] [<ffffffff815782e3>] __fput+0x263/0x700 [ 31.760029] [<ffffffff81578805>] ____fput+0x15/0x20 [ 31.765104] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 31.770788] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 31.777347] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 31.783040] [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.789957] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 31.817125] RIP [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 31.823652] RSP <ffff8801b62f7ca0> [ 31.827258] CR2: 0000000000000080 [ 31.830787] ---[ end trace 6fc2a838ae7cc339 ]--- [ 31.835536] Kernel panic - not syncing: Fatal exception [ 31.841287] Dumping ftrace buffer: [ 31.844798] (ftrace buffer empty) [ 31.848482] Kernel Offset: disabled [ 31.852083] Rebooting in 86400 seconds..