[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.630831] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.573816] random: sshd: uninitialized urandom read (32 bytes read) [ 22.940175] random: sshd: uninitialized urandom read (32 bytes read) [ 23.466087] random: sshd: uninitialized urandom read (32 bytes read) [ 23.615959] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.10' (ECDSA) to the list of known hosts. [ 29.019916] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.216770] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.225086] IP: [] l2tp_session_free+0x11c/0x200 [ 29.231520] PGD 1c5490067 [ 29.234189] PUD 1c627d067 PMD 0 [ 29.237684] [ 29.239307] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.243781] Dumping ftrace buffer: [ 29.247399] (ftrace buffer empty) [ 29.251092] Modules linked in: [ 29.254393] CPU: 1 PID: 3740 Comm: syz-executor052 Not tainted 4.9.118-g856452b #73 [ 29.262162] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.271495] task: ffff8801bfc93000 task.stack: ffff8801be3a0000 [ 29.277579] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 29.286464] RSP: 0018:ffff8801be3a7ca0 EFLAGS: 00010246 [ 29.291902] RAX: dffffc0000000000 RBX: ffff8801caa9e500 RCX: 0000000000000000 [ 29.299272] RDX: 1ffff10037c39e60 RSI: ffffffff836bf781 RDI: ffff8801be1cf300 [ 29.306526] RBP: ffff8801be3a7cc0 R08: ffff8801bfc938e8 R09: 0000000000000000 [ 29.313781] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801be1cf180 [ 29.321039] R13: ffff8801caa9e508 R14: 0000000000000000 R15: ffffffff83015be0 [ 29.328296] FS: 0000000001000880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 29.336509] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.342381] CR2: 0000000000000080 CR3: 00000001c6352000 CR4: 00000000001606f0 [ 29.349654] Stack: [ 29.351787] ffff8801be76cc80 ffff8801caa9e500 ffff8801be76d050 ffff8801be76cf58 [ 29.359945] ffff8801be3a7ce8 ffffffff836c7092 ffff8801be76d0c0 ffff8801be76cc80 [ 29.367971] ffffffff836c6fc0 ffff8801be3a7d20 ffffffff830230f5 ffff8801be76d0c0 [ 29.376080] Call Trace: [ 29.378651] [] pppol2tp_session_destruct+0xd2/0x110 [ 29.385317] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 29.391683] [] __sk_destruct+0x55/0x590 [ 29.397293] [] ? sock_release+0x1c0/0x1c0 [ 29.403067] [] sk_destruct+0x63/0x80 [ 29.408411] [] __sk_free+0x4f/0x220 [ 29.413765] [] sk_free+0x2b/0x40 [ 29.418764] [] pppol2tp_release+0x239/0x2e0 [ 29.424898] [] sock_release+0x96/0x1c0 [ 29.430416] [] sock_close+0x16/0x20 [ 29.435676] [] __fput+0x263/0x700 [ 29.440828] [] ____fput+0x15/0x20 [ 29.445915] [] task_work_run+0x10c/0x180 [ 29.451649] [] exit_to_usermode_loop+0xfc/0x120 [ 29.457951] [] do_syscall_64+0x364/0x490 [ 29.463649] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.470609] 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 [ 29.497618] RIP [] l2tp_session_free+0x11c/0x200 [ 29.504151] RSP [ 29.507753] CR2: 0000000000000080 [ 29.511298] ---[ end trace 481bd892d29acb69 ]--- [ 29.516596] Kernel panic - not syncing: Fatal exception [ 29.522237] Dumping ftrace buffer: [ 29.525769] (ftrace buffer empty) [ 29.529459] Kernel Offset: disabled [ 29.533063] Rebooting in 86400 seconds..