[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.024462] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.137519] random: sshd: uninitialized urandom read (32 bytes read) [ 17.528229] random: sshd: uninitialized urandom read (32 bytes read) [ 18.058795] random: sshd: uninitialized urandom read (32 bytes read) [ 24.404303] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.63' (ECDSA) to the list of known hosts. [ 29.803937] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.002713] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.010944] IP: [] l2tp_session_free+0x11c/0x200 [ 30.017509] PGD 1bf836067 [ 30.020152] PUD 1bed79067 PMD 0 [ 30.023628] [ 30.025268] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.029741] Dumping ftrace buffer: [ 30.033338] (ftrace buffer empty) [ 30.037037] Modules linked in: [ 30.040337] CPU: 1 PID: 3742 Comm: syz-executor204 Not tainted 4.9.119-g92e8704 #74 [ 30.048235] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.057579] task: ffff8801bf9fe000 task.stack: ffff8801bd6d8000 [ 30.063612] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.072476] RSP: 0018:ffff8801bd6dfca0 EFLAGS: 00010246 [ 30.077955] RAX: dffffc0000000000 RBX: ffff8801cc519400 RCX: 0000000000000000 [ 30.085211] RDX: 1ffff10037a82f00 RSI: ffffffff836bf9a1 RDI: ffff8801bd417800 [ 30.092467] RBP: ffff8801bd6dfcc0 R08: ffff8801bf9fe8e8 R09: 0000000000000000 [ 30.099734] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bd417680 [ 30.107054] R13: ffff8801cc519408 R14: 0000000000000000 R15: ffffffff83015be0 [ 30.114375] FS: 00000000017e3880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 30.122618] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.128531] CR2: 0000000000000080 CR3: 00000001be45e000 CR4: 00000000001606f0 [ 30.135854] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.143123] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.150376] Stack: [ 30.152507] ffff8801bdf0aa80 ffff8801cc519400 ffff8801bdf0ae50 ffff8801bdf0ad58 [ 30.160607] ffff8801bd6dfce8 ffffffff836c72b2 ffff8801bdf0aec0 ffff8801bdf0aa80 [ 30.168594] ffffffff836c71e0 ffff8801bd6dfd20 ffffffff830230f5 ffff8801bdf0aec0 [ 30.176584] Call Trace: [ 30.179182] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.185837] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.192149] [] __sk_destruct+0x55/0x590 [ 30.197944] [] ? sock_release+0x1c0/0x1c0 [ 30.203789] [] sk_destruct+0x63/0x80 [ 30.209141] [] __sk_free+0x4f/0x220 [ 30.214397] [] sk_free+0x2b/0x40 [ 30.219403] [] pppol2tp_release+0x239/0x2e0 [ 30.225369] [] sock_release+0x96/0x1c0 [ 30.230894] [] sock_close+0x16/0x20 [ 30.236163] [] __fput+0x263/0x700 [ 30.241246] [] ____fput+0x15/0x20 [ 30.246337] [] task_work_run+0x10c/0x180 [ 30.252028] [] exit_to_usermode_loop+0xfc/0x120 [ 30.258327] [] do_syscall_64+0x364/0x490 [ 30.264023] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.271146] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 30.298024] RIP [] l2tp_session_free+0x11c/0x200 [ 30.304531] RSP [ 30.308216] CR2: 0000000000000080 [ 30.311975] ---[ end trace 7c87aea03406c9d9 ]--- [ 30.316748] Kernel panic - not syncing: Fatal exception [ 30.322478] Dumping ftrace buffer: [ 30.326058] (ftrace buffer empty) [ 30.329760] Kernel Offset: disabled [ 30.333363] Rebooting in 86400 seconds..