[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.556708] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.848298] random: sshd: uninitialized urandom read (32 bytes read) [ 20.301032] random: sshd: uninitialized urandom read (32 bytes read) [ 20.842182] random: sshd: uninitialized urandom read (32 bytes read) [ 20.985633] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.28' (ECDSA) to the list of known hosts. [ 26.601979] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.808279] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.816695] IP: [] l2tp_session_free+0x11c/0x200 [ 26.823256] PGD 1c6949067 [ 26.825899] PUD 1c42f0067 PMD 0 [ 26.829378] [ 26.831012] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.835484] Dumping ftrace buffer: [ 26.838999] (ftrace buffer empty) [ 26.842685] Modules linked in: [ 26.845986] CPU: 0 PID: 3744 Comm: syz-executor093 Not tainted 4.9.122-g54068d6 #78 [ 26.853762] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.863094] task: ffff8801be9bc800 task.stack: ffff8801bd530000 [ 26.869125] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.877981] RSP: 0018:ffff8801bd537ca0 EFLAGS: 00010246 [ 26.883409] RAX: dffffc0000000000 RBX: ffff8801bd9c3b80 RCX: 0000000000000000 [ 26.890654] RDX: 1ffff10037ab32b0 RSI: ffffffff836c39a1 RDI: ffff8801bd599580 [ 26.897904] RBP: ffff8801bd537cc0 R08: ffff8801be9bd0e8 R09: 0000000000000000 [ 26.905153] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bd599400 [ 26.912398] R13: ffff8801bd9c3b88 R14: 0000000000000000 R15: ffffffff83019be0 [ 26.919647] FS: 0000000001e55880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 26.927865] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.933784] CR2: 0000000000000080 CR3: 00000001c6948000 CR4: 00000000001606f0 [ 26.941038] Stack: [ 26.943166] ffff8801bda45500 ffff8801bd9c3b80 ffff8801bda458d0 ffff8801bda457d8 [ 26.951180] ffff8801bd537ce8 ffffffff836cb2b2 ffff8801bda45940 ffff8801bda45500 [ 26.959182] ffffffff836cb1e0 ffff8801bd537d20 ffffffff830270f5 ffff8801bda45940 [ 26.967174] Call Trace: [ 26.969746] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.976390] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.982789] [] __sk_destruct+0x55/0x590 [ 26.988441] [] ? sock_release+0x1c0/0x1c0 [ 26.994274] [] sk_destruct+0x63/0x80 [ 26.999624] [] __sk_free+0x4f/0x220 [ 27.004877] [] sk_free+0x2b/0x40 [ 27.009868] [] pppol2tp_release+0x239/0x2e0 [ 27.015824] [] sock_release+0x96/0x1c0 [ 27.021342] [] sock_close+0x16/0x20 [ 27.026594] [] __fput+0x263/0x700 [ 27.031677] [] ____fput+0x15/0x20 [ 27.036759] [] task_work_run+0x10c/0x180 [ 27.042452] [] exit_to_usermode_loop+0xfc/0x120 [ 27.048748] [] do_syscall_64+0x364/0x490 [ 27.054442] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.061345] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 27.088386] RIP [] l2tp_session_free+0x11c/0x200 [ 27.094929] RSP [ 27.098543] CR2: 0000000000000080 [ 27.102249] ---[ end trace 7ff6134c906cd950 ]--- [ 27.106992] Kernel panic - not syncing: Fatal exception [ 27.112655] Dumping ftrace buffer: [ 27.116179] (ftrace buffer empty) [ 27.119866] Kernel Offset: disabled [ 27.123469] Rebooting in 86400 seconds..