[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 17.368974] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.043823] random: sshd: uninitialized urandom read (32 bytes read) [ 22.320252] random: sshd: uninitialized urandom read (32 bytes read) [ 22.783806] random: sshd: uninitialized urandom read (32 bytes read) [ 36.185042] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.15' (ECDSA) to the list of known hosts. [ 41.825935] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 42.029644] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 42.037890] IP: [<ffffffff836c29cc>] l2tp_session_free+0x11c/0x200 [ 42.044390] PGD 1c9f60067 [ 42.047045] PUD 1c9f58067 PMD 0 [ 42.050539] [ 42.052160] Oops: 0002 [#1] PREEMPT SMP KASAN [ 42.056625] Dumping ftrace buffer: [ 42.060237] (ftrace buffer empty) [ 42.064010] Modules linked in: [ 42.067345] CPU: 0 PID: 3814 Comm: syz-executor628 Not tainted 4.9.120-gf85543b #76 [ 42.075230] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.084564] task: ffff8801b5788000 task.stack: ffff8801b56d0000 [ 42.090687] RIP: 0010:[<ffffffff836c29cc>] [<ffffffff836c29cc>] l2tp_session_free+0x11c/0x200 [ 42.099660] RSP: 0018:ffff8801b56d7ca0 EFLAGS: 00010246 [ 42.105096] RAX: dffffc0000000000 RBX: ffff8801b5b08000 RCX: 0000000000000000 [ 42.112347] RDX: 1ffff10036a8ad70 RSI: ffffffff836c29a1 RDI: ffff8801b5456b80 [ 42.119598] RBP: ffff8801b56d7cc0 R08: ffff8801b57888e8 R09: 0000000000000000 [ 42.126848] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5456a00 [ 42.134215] R13: ffff8801b5b08008 R14: 0000000000000000 R15: ffffffff83018be0 [ 42.141479] FS: 00000000006ea880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 42.149784] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 42.155655] CR2: 0000000000000080 CR3: 00000001c9f66000 CR4: 00000000001606f0 [ 42.163010] Stack: [ 42.165153] ffff8801b551a200 ffff8801b5b08000 ffff8801b551a5d0 ffff8801b551a4d8 [ 42.173160] ffff8801b56d7ce8 ffffffff836ca2b2 ffff8801b551a640 ffff8801b551a200 [ 42.181185] ffffffff836ca1e0 ffff8801b56d7d20 ffffffff830260f5 ffff8801b551a640 [ 42.189177] Call Trace: [ 42.191818] [<ffffffff836ca2b2>] pppol2tp_session_destruct+0xd2/0x110 [ 42.198583] [<ffffffff836ca1e0>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 42.204885] [<ffffffff830260f5>] __sk_destruct+0x55/0x590 [ 42.210492] [<ffffffff83018be0>] ? sock_release+0x1c0/0x1c0 [ 42.216264] [<ffffffff8302db83>] sk_destruct+0x63/0x80 [ 42.221669] [<ffffffff8302dbef>] __sk_free+0x4f/0x220 [ 42.226928] [<ffffffff8302ddeb>] sk_free+0x2b/0x40 [ 42.231920] [<ffffffff836cd5b9>] pppol2tp_release+0x239/0x2e0 [ 42.237863] [<ffffffff83018ab6>] sock_release+0x96/0x1c0 [ 42.243385] [<ffffffff83018bf6>] sock_close+0x16/0x20 [ 42.248650] [<ffffffff8157b293>] __fput+0x263/0x700 [ 42.253730] [<ffffffff8157b7b5>] ____fput+0x15/0x20 [ 42.258873] [<ffffffff8119a0ac>] task_work_run+0x10c/0x180 [ 42.264572] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 42.270870] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 42.276574] [<ffffffff839ffcd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 42.283691] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 15 de c9 fd 4c 89 ea 48 b8 00 [ 42.310629] RIP [<ffffffff836c29cc>] l2tp_session_free+0x11c/0x200 [ 42.317139] RSP <ffff8801b56d7ca0> [ 42.320737] CR2: 0000000000000080 [ 42.324411] ---[ end trace 01c492f0b9bcc2ff ]--- [ 42.329165] Kernel panic - not syncing: Fatal exception [ 42.334775] Dumping ftrace buffer: [ 42.338292] (ftrace buffer empty) [ 42.341978] Kernel Offset: disabled [ 42.345609] Rebooting in 86400 seconds..