[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.834197] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.731436] random: sshd: uninitialized urandom read (32 bytes read) [ 21.106259] random: sshd: uninitialized urandom read (32 bytes read) [ 22.056618] random: sshd: uninitialized urandom read (32 bytes read) [ 22.201573] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.49' (ECDSA) to the list of known hosts. [ 27.598217] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.818390] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.826617] IP: [] l2tp_session_free+0x11c/0x200 [ 27.833038] PGD 1bbdc5067 [ 27.835679] PUD 1bbdc1067 PMD 0 [ 27.839158] [ 27.840781] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.845249] Dumping ftrace buffer: [ 27.848761] (ftrace buffer empty) [ 27.852444] Modules linked in: [ 27.855736] CPU: 1 PID: 3798 Comm: syz-executor021 Not tainted 4.9.113-g90e7a90 #16 [ 27.863502] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.872838] task: ffff8801b81f4800 task.stack: ffff8801d97e8000 [ 27.878868] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.887715] RSP: 0018:ffff8801d97efca0 EFLAGS: 00010246 [ 27.893136] RAX: dffffc0000000000 RBX: ffff8801b64b0780 RCX: 0000000000000000 [ 27.900393] RDX: 1ffff10039662b50 RSI: ffffffff836bdee1 RDI: ffff8801cb315a80 [ 27.907672] RBP: ffff8801d97efcc0 R08: ffff8801b81f50e8 R09: 0000000000000000 [ 27.914919] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb315900 [ 27.922164] R13: ffff8801b64b0788 R14: 0000000000000000 R15: ffffffff83014be0 [ 27.929415] FS: 0000000000ad7880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.937628] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.943487] CR2: 0000000000000080 CR3: 00000001b6aa2000 CR4: 00000000001606f0 [ 27.950732] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.957975] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.965218] Stack: [ 27.967344] ffff8801d95c4400 ffff8801b64b0780 ffff8801d95c47d0 ffff8801d95c46d8 [ 27.975351] ffff8801d97efce8 ffffffff836c57f2 ffff8801d95c4840 ffff8801d95c4400 [ 27.983354] ffffffff836c5720 ffff8801d97efd20 ffffffff83022095 ffff8801d95c4840 [ 27.991344] Call Trace: [ 27.993909] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.000551] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.006845] [] __sk_destruct+0x55/0x590 [ 28.012451] [] ? sock_release+0x1c0/0x1c0 [ 28.018229] [] sk_destruct+0x63/0x80 [ 28.023572] [] __sk_free+0x4f/0x220 [ 28.028820] [] sk_free+0x2b/0x40 [ 28.033808] [] pppol2tp_release+0x239/0x2e0 [ 28.039764] [] sock_release+0x96/0x1c0 [ 28.045276] [] sock_close+0x16/0x20 [ 28.050530] [] __fput+0x263/0x700 [ 28.055616] [] ____fput+0x15/0x20 [ 28.060692] [] task_work_run+0x10c/0x180 [ 28.066391] [] exit_to_usermode_loop+0xfc/0x120 [ 28.072683] [] do_syscall_64+0x364/0x490 [ 28.078368] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.085271] 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 0b ca fd 4c 89 ea 48 b8 00 [ 28.112144] RIP [] l2tp_session_free+0x11c/0x200 [ 28.118655] RSP [ 28.122252] CR2: 0000000000000080 [ 28.126002] ---[ end trace 9cba66be319edc5a ]--- [ 28.130765] Kernel panic - not syncing: Fatal exception [ 28.136580] Dumping ftrace buffer: [ 28.140100] (ftrace buffer empty) [ 28.143796] Kernel Offset: disabled [ 28.147398] Rebooting in 86400 seconds..