[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.099145] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.370052] random: sshd: uninitialized urandom read (32 bytes read) [ 17.673401] random: sshd: uninitialized urandom read (32 bytes read) [ 18.602093] random: sshd: uninitialized urandom read (32 bytes read) [ 18.743359] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.17' (ECDSA) to the list of known hosts. [ 24.305448] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.514193] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.522427] IP: [] l2tp_session_free+0x11c/0x200 [ 24.528860] PGD 1c9f12067 [ 24.531513] PUD 1c9fac067 PMD 0 [ 24.535004] [ 24.536627] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.541097] Dumping ftrace buffer: [ 24.544609] (ftrace buffer empty) [ 24.548294] Modules linked in: [ 24.551593] CPU: 0 PID: 3799 Comm: syz-executor931 Not tainted 4.9.113-g47bbcd6 #10 [ 24.559367] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.568696] task: ffff8801b8573000 task.stack: ffff8801d9678000 [ 24.574726] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.583596] RSP: 0018:ffff8801d967fca0 EFLAGS: 00010246 [ 24.589022] RAX: dffffc0000000000 RBX: ffff8801b60c9b80 RCX: 0000000000000000 [ 24.596280] RDX: 1ffff10038f94c30 RSI: ffffffff836bcce1 RDI: ffff8801c7ca6180 [ 24.603526] RBP: ffff8801d967fcc0 R08: ffff8801b85738e8 R09: 0000000000000000 [ 24.610771] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c7ca6000 [ 24.618017] R13: ffff8801b60c9b88 R14: 0000000000000000 R15: ffffffff83013be0 [ 24.625265] FS: 00000000023fc880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.633464] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.639320] CR2: 0000000000000080 CR3: 00000001c1562000 CR4: 00000000001606f0 [ 24.646566] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.653812] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.661056] Stack: [ 24.663177] ffff8801b60a4400 ffff8801b60c9b80 ffff8801b60a47d0 ffff8801b60a46d8 [ 24.671209] ffff8801d967fce8 ffffffff836c45f2 ffff8801b60a4840 ffff8801b60a4400 [ 24.679222] ffffffff836c4520 ffff8801d967fd20 ffffffff83021095 ffff8801b60a4840 [ 24.687248] Call Trace: [ 24.689815] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.696454] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.702747] [] __sk_destruct+0x55/0x590 [ 24.708345] [] ? sock_release+0x1c0/0x1c0 [ 24.714113] [] sk_destruct+0x63/0x80 [ 24.719447] [] __sk_free+0x4f/0x220 [ 24.724710] [] sk_free+0x2b/0x40 [ 24.729698] [] pppol2tp_release+0x239/0x2e0 [ 24.735652] [] sock_release+0x96/0x1c0 [ 24.741174] [] sock_close+0x16/0x20 [ 24.746439] [] __fput+0x263/0x700 [ 24.751519] [] ____fput+0x15/0x20 [ 24.756596] [] task_work_run+0x10c/0x180 [ 24.762281] [] exit_to_usermode_loop+0xfc/0x120 [ 24.768572] [] do_syscall_64+0x364/0x490 [ 24.774256] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.781150] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 24.808201] RIP [] l2tp_session_free+0x11c/0x200 [ 24.814712] RSP [ 24.818307] CR2: 0000000000000080 [ 24.822128] ---[ end trace 83cc3ac8b7ae7615 ]--- [ 24.826882] Kernel panic - not syncing: Fatal exception [ 24.832645] Dumping ftrace buffer: [ 24.836169] (ftrace buffer empty) [ 24.839853] Kernel Offset: disabled [ 24.843473] Rebooting in 86400 seconds..