[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.409367] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.085628] random: sshd: uninitialized urandom read (32 bytes read) [ 16.289732] random: sshd: uninitialized urandom read (32 bytes read) [ 16.769056] random: sshd: uninitialized urandom read (32 bytes read) [ 21.017439] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.27' (ECDSA) to the list of known hosts. [ 26.764052] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.965844] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.974076] IP: [] l2tp_session_free+0x11c/0x200 [ 26.980497] PGD 1c83c9067 [ 26.983144] PUD 1c7118067 PMD 0 [ 26.986628] [ 26.988256] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.992731] Dumping ftrace buffer: [ 26.996343] (ftrace buffer empty) [ 27.000041] Modules linked in: [ 27.003339] CPU: 1 PID: 3795 Comm: syz-executor192 Not tainted 4.9.121-g681e57b #25 [ 27.011106] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.020436] task: ffff8801b8b61800 task.stack: ffff8801d9b80000 [ 27.026469] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.035352] RSP: 0018:ffff8801d9b87ca0 EFLAGS: 00010246 [ 27.040798] RAX: dffffc0000000000 RBX: ffff8801b73d2f00 RCX: 0000000000000000 [ 27.048059] RDX: 1ffff10036db6e60 RSI: ffffffff836c29a1 RDI: ffff8801b6db7300 [ 27.055360] RBP: ffff8801d9b87cc0 R08: ffff8801b8b620e8 R09: 0000000000000000 [ 27.062614] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6db7180 [ 27.069860] R13: ffff8801b73d2f08 R14: 0000000000000000 R15: ffffffff83018be0 [ 27.077107] FS: 0000000000edb880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.085310] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.091172] CR2: 0000000000000080 CR3: 00000001ca80f000 CR4: 00000000001606f0 [ 27.098430] Stack: [ 27.100555] ffff8801b69f5500 ffff8801b73d2f00 ffff8801b69f58d0 ffff8801b69f57d8 [ 27.108559] ffff8801d9b87ce8 ffffffff836ca2b2 ffff8801b69f5940 ffff8801b69f5500 [ 27.116577] ffffffff836ca1e0 ffff8801d9b87d20 ffffffff830260f5 ffff8801b69f5940 [ 27.124580] Call Trace: [ 27.127146] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.133799] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.140093] [] __sk_destruct+0x55/0x590 [ 27.145701] [] ? sock_release+0x1c0/0x1c0 [ 27.151479] [] sk_destruct+0x63/0x80 [ 27.156828] [] __sk_free+0x4f/0x220 [ 27.162089] [] sk_free+0x2b/0x40 [ 27.167085] [] pppol2tp_release+0x239/0x2e0 [ 27.173035] [] sock_release+0x96/0x1c0 [ 27.178549] [] sock_close+0x16/0x20 [ 27.183811] [] __fput+0x263/0x700 [ 27.188903] [] ____fput+0x15/0x20 [ 27.193986] [] task_work_run+0x10c/0x180 [ 27.199692] [] exit_to_usermode_loop+0xfc/0x120 [ 27.205992] [] do_syscall_64+0x364/0x490 [ 27.211684] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.218583] 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 65 df c9 fd 4c 89 ea 48 b8 00 [ 27.245957] RIP [] l2tp_session_free+0x11c/0x200 [ 27.252515] RSP [ 27.256120] CR2: 0000000000000080 [ 27.259678] ---[ end trace ef3c974708841a12 ]--- [ 27.264433] Kernel panic - not syncing: Fatal exception [ 27.270077] Dumping ftrace buffer: [ 27.273605] (ftrace buffer empty) [ 27.277292] Kernel Offset: disabled [ 27.280893] Rebooting in 86400 seconds..