[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.008465] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.981881] random: sshd: uninitialized urandom read (32 bytes read) [ 20.379649] random: sshd: uninitialized urandom read (32 bytes read) [ 20.868298] random: sshd: uninitialized urandom read (32 bytes read) [ 20.998503] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.37' (ECDSA) to the list of known hosts. [ 26.715365] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.923791] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.932184] IP: [] l2tp_session_free+0x11c/0x200 [ 26.938811] PGD 1c0348067 [ 26.941462] PUD 1c02d2067 PMD 0 [ 26.944958] [ 26.946596] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.951071] Dumping ftrace buffer: [ 26.954588] (ftrace buffer empty) [ 26.958381] Modules linked in: [ 26.961674] CPU: 1 PID: 3764 Comm: syz-executor042 Not tainted 4.9.123-g7fa8c15 #28 [ 26.969584] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.978926] task: ffff8801bd62e000 task.stack: ffff8801bb850000 [ 26.984962] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.993965] RSP: 0018:ffff8801bb857c98 EFLAGS: 00010246 [ 26.999482] RAX: dffffc0000000000 RBX: ffff8801bbfe5680 RCX: 0000000000000000 [ 27.006740] RDX: 1ffff10037721300 RSI: ffffffff836c4a91 RDI: ffff8801bb909800 [ 27.013993] RBP: ffff8801bb857cb8 R08: ffff8801bd62e8e8 R09: 0000000000000000 [ 27.021250] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bb909680 [ 27.028514] R13: ffff8801bbfe5688 R14: 0000000000000000 R15: 0000000000000000 [ 27.035767] FS: 0000000002454880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.044077] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.049943] CR2: 0000000000000080 CR3: 00000001c2ca9000 CR4: 00000000001606f0 [ 27.057197] Stack: [ 27.059336] ffff8801bb92a200 ffff8801bbfe5680 ffff8801bb92a5d0 ffff8801bb92a4d8 [ 27.067448] ffff8801bb857ce0 ffffffff836cc3a2 ffff8801bb92a640 ffff8801bb92a200 [ 27.075549] ffffffff836cc2d0 ffff8801bb857d18 ffffffff830281f5 ffff8801bb92a640 [ 27.083553] Call Trace: [ 27.086169] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.092923] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.099229] [] __sk_destruct+0x55/0x590 [ 27.104838] [] sk_destruct+0x63/0x80 [ 27.110191] [] __sk_free+0x4f/0x220 [ 27.115459] [] sk_free+0x2b/0x40 [ 27.120454] [] pppol2tp_release+0x239/0x2e0 [ 27.126521] [] __sock_release+0xd7/0x260 [ 27.132212] [] ? __sock_release+0x260/0x260 [ 27.138165] [] sock_close+0x19/0x20 [ 27.143536] [] __fput+0x263/0x700 [ 27.148628] [] ____fput+0x15/0x20 [ 27.153737] [] task_work_run+0x10c/0x180 [ 27.159443] [] exit_to_usermode_loop+0xfc/0x120 [ 27.165745] [] do_syscall_64+0x364/0x490 [ 27.171498] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.178405] 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 c2 c9 fd 4c 89 ea 48 b8 00 [ 27.205636] RIP [] l2tp_session_free+0x11c/0x200 [ 27.212286] RSP [ 27.215899] CR2: 0000000000000080 [ 27.219864] ---[ end trace 92745b116a66b558 ]--- [ 27.224657] Kernel panic - not syncing: Fatal exception [ 27.230421] Dumping ftrace buffer: [ 27.233957] (ftrace buffer empty) [ 27.237644] Kernel Offset: disabled [ 27.241250] Rebooting in 86400 seconds..