[....] 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[ 14.641110] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.036190] random: sshd: uninitialized urandom read (32 bytes read) [ 18.227245] random: sshd: uninitialized urandom read (32 bytes read) [ 18.721053] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.61' (ECDSA) to the list of known hosts. [ 24.265830] urandom_read: 1 callbacks suppressed [ 24.265834] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.478845] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.487060] IP: [] l2tp_session_free+0x11c/0x200 [ 24.493503] PGD 1c9eb4067 [ 24.496231] PUD 1c6055067 PMD 0 [ 24.499716] [ 24.501341] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.505809] Dumping ftrace buffer: [ 24.509322] (ftrace buffer empty) [ 24.513008] Modules linked in: [ 24.516294] CPU: 1 PID: 3715 Comm: syz-executor213 Not tainted 4.9.119-g9dc978d #75 [ 24.524059] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.533399] task: ffff8801c0b41800 task.stack: ffff8801bfaf0000 [ 24.539429] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.548274] RSP: 0018:ffff8801bfaf7ca0 EFLAGS: 00010246 [ 24.553711] RAX: dffffc0000000000 RBX: ffff8801cc5a5b80 RCX: 0000000000000000 [ 24.560954] RDX: 1ffff10037f5ad70 RSI: ffffffff836bf9a1 RDI: ffff8801bfad6b80 [ 24.568197] RBP: ffff8801bfaf7cc0 R08: ffff8801c0b420e8 R09: 0000000000000000 [ 24.575444] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bfad6a00 [ 24.582694] R13: ffff8801cc5a5b88 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.589957] FS: 0000000001ad9880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 24.598167] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.604021] CR2: 0000000000000080 CR3: 00000001c571d000 CR4: 00000000001606f0 [ 24.611279] Stack: [ 24.613403] ffff8801bfa94400 ffff8801cc5a5b80 ffff8801bfa947d0 ffff8801bfa946d8 [ 24.621409] ffff8801bfaf7ce8 ffffffff836c72b2 ffff8801bfa94840 ffff8801bfa94400 [ 24.629415] ffffffff836c71e0 ffff8801bfaf7d20 ffffffff830230f5 ffff8801bfa94840 [ 24.637423] Call Trace: [ 24.639987] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.646644] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.652944] [] __sk_destruct+0x55/0x590 [ 24.658541] [] ? sock_release+0x1c0/0x1c0 [ 24.664327] [] sk_destruct+0x63/0x80 [ 24.669664] [] __sk_free+0x4f/0x220 [ 24.674915] [] sk_free+0x2b/0x40 [ 24.679911] [] pppol2tp_release+0x239/0x2e0 [ 24.685862] [] sock_release+0x96/0x1c0 [ 24.691376] [] sock_close+0x16/0x20 [ 24.696645] [] __fput+0x263/0x700 [ 24.701723] [] ____fput+0x15/0x20 [ 24.706802] [] task_work_run+0x10c/0x180 [ 24.712500] [] exit_to_usermode_loop+0xfc/0x120 [ 24.718803] [] do_syscall_64+0x364/0x490 [ 24.724489] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.731390] 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 [ 24.751926] RIP [ 24.751951] [] l2tp_session_free+0x11c/0x200 RSP [ 24.751956] CR2: 0000000000000080 [ 24.755448] ---[ end trace cb9d80fd83ef058e ]--- [ 24.755452] Kernel panic - not syncing: Fatal exception [ 24.755775] Dumping ftrace buffer: [ 24.755778] (ftrace buffer empty) [ 24.755781] Kernel Offset: disabled [ 24.791743] Rebooting in 86400 seconds..