[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.330486] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.470628] random: sshd: uninitialized urandom read (32 bytes read) [ 21.753844] random: sshd: uninitialized urandom read (32 bytes read) [ 22.218810] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.52' (ECDSA) to the list of known hosts. [ 27.763469] urandom_read: 1 callbacks suppressed [ 27.763474] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.967446] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.975753] IP: [] l2tp_session_free+0x11c/0x200 [ 27.982191] PGD 1c5088067 [ 27.984915] PUD 1c5243067 PMD 0 [ 27.988409] [ 27.990034] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.994515] Dumping ftrace buffer: [ 27.998041] (ftrace buffer empty) [ 28.001731] Modules linked in: [ 28.005034] CPU: 0 PID: 3808 Comm: syz-executor739 Not tainted 4.9.118-g47b77b8 #72 [ 28.012807] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.022244] task: ffff8801b6040000 task.stack: ffff8801cadc0000 [ 28.028302] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.037177] RSP: 0018:ffff8801cadc7ca0 EFLAGS: 00010246 [ 28.042668] RAX: dffffc0000000000 RBX: ffff8801b514c280 RCX: 0000000000000000 [ 28.049926] RDX: 1ffff10036c3e260 RSI: ffffffff836bf781 RDI: ffff8801b61f1300 [ 28.057181] RBP: ffff8801cadc7cc0 R08: ffff8801b60408e8 R09: 0000000000000000 [ 28.064430] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b61f1180 [ 28.071678] R13: ffff8801b514c288 R14: 0000000000000000 R15: ffffffff83015be0 [ 28.078928] FS: 00000000008f0880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 28.087136] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.093118] CR2: 0000000000000080 CR3: 00000001c513e000 CR4: 00000000001606f0 [ 28.100369] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.107622] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.114882] Stack: [ 28.117012] ffff8801b51ae600 ffff8801b514c280 ffff8801b51ae9d0 ffff8801b51ae8d8 [ 28.125082] ffff8801cadc7ce8 ffffffff836c7092 ffff8801b51aea40 ffff8801b51ae600 [ 28.133092] ffffffff836c6fc0 ffff8801cadc7d20 ffffffff830230f5 ffff8801b51aea40 [ 28.141092] Call Trace: [ 28.143665] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.150382] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.156696] [] __sk_destruct+0x55/0x590 [ 28.162302] [] ? sock_release+0x1c0/0x1c0 [ 28.168077] [] sk_destruct+0x63/0x80 [ 28.173525] [] __sk_free+0x4f/0x220 [ 28.178798] [] sk_free+0x2b/0x40 [ 28.183920] [] pppol2tp_release+0x239/0x2e0 [ 28.189890] [] sock_release+0x96/0x1c0 [ 28.195416] [] sock_close+0x16/0x20 [ 28.200677] [] __fput+0x263/0x700 [ 28.205756] [] ____fput+0x15/0x20 [ 28.210848] [] task_work_run+0x10c/0x180 [ 28.216551] [] exit_to_usermode_loop+0xfc/0x120 [ 28.222858] [] do_syscall_64+0x364/0x490 [ 28.228551] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.235449] 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 f2 c9 fd 4c 89 ea 48 b8 00 [ 28.262779] RIP [] l2tp_session_free+0x11c/0x200 [ 28.269398] RSP [ 28.273003] CR2: 0000000000000080 [ 28.276775] ---[ end trace f1ed393acd60fa18 ]--- [ 28.281549] Kernel panic - not syncing: Fatal exception [ 28.287072] Dumping ftrace buffer: [ 28.290598] (ftrace buffer empty) [ 28.294291] Kernel Offset: disabled [ 28.297904] Rebooting in 86400 seconds..