[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.587945] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.805149] random: sshd: uninitialized urandom read (32 bytes read) [ 18.119292] random: sshd: uninitialized urandom read (32 bytes read) [ 18.621907] random: sshd: uninitialized urandom read (32 bytes read) [ 19.013871] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.2' (ECDSA) to the list of known hosts. [ 24.456566] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.679920] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.688288] IP: [] l2tp_session_free+0x11c/0x200 [ 24.694741] PGD 1ca51c067 [ 24.697386] PUD 1cae89067 PMD 0 [ 24.700982] [ 24.702604] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.707082] Dumping ftrace buffer: [ 24.710596] (ftrace buffer empty) [ 24.714282] Modules linked in: [ 24.717650] CPU: 1 PID: 3793 Comm: syz-executor302 Not tainted 4.9.118-g856452b #73 [ 24.725519] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.734855] task: ffff8801b8dce000 task.stack: ffff8801b73a0000 [ 24.740891] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.749759] RSP: 0018:ffff8801b73a7ca0 EFLAGS: 00010246 [ 24.755192] RAX: dffffc0000000000 RBX: ffff8801b6d3e780 RCX: 0000000000000000 [ 24.762449] RDX: 1ffff1003948b7a0 RSI: ffffffff836bf781 RDI: ffff8801ca45bd00 [ 24.769710] RBP: ffff8801b73a7cc0 R08: ffff8801b8dce8e8 R09: 0000000000000000 [ 24.776967] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca45bb80 [ 24.784221] R13: ffff8801b6d3e788 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.791486] FS: 0000000001ec8880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 24.799743] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.805613] CR2: 0000000000000080 CR3: 00000001b73ee000 CR4: 00000000001606f0 [ 24.812865] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.820123] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.827374] Stack: [ 24.829502] ffff8801b7336600 ffff8801b6d3e780 ffff8801b73369d0 ffff8801b73368d8 [ 24.837514] ffff8801b73a7ce8 ffffffff836c7092 ffff8801b7336a40 ffff8801b7336600 [ 24.845515] ffffffff836c6fc0 ffff8801b73a7d20 ffffffff830230f5 ffff8801b7336a40 [ 24.853514] Call Trace: [ 24.856082] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.862893] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.869198] [] __sk_destruct+0x55/0x590 [ 24.874816] [] ? sock_release+0x1c0/0x1c0 [ 24.880602] [] sk_destruct+0x63/0x80 [ 24.885948] [] __sk_free+0x4f/0x220 [ 24.891215] [] sk_free+0x2b/0x40 [ 24.896222] [] pppol2tp_release+0x239/0x2e0 [ 24.902228] [] sock_release+0x96/0x1c0 [ 24.907750] [] sock_close+0x16/0x20 [ 24.913012] [] __fput+0x263/0x700 [ 24.918102] [] ____fput+0x15/0x20 [ 24.923183] [] task_work_run+0x10c/0x180 [ 24.928874] [] exit_to_usermode_loop+0xfc/0x120 [ 24.935175] [] do_syscall_64+0x364/0x490 [ 24.940863] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.947766] 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 [ 24.974950] RIP [] l2tp_session_free+0x11c/0x200 [ 24.981457] RSP [ 24.985055] CR2: 0000000000000080 [ 24.988848] ---[ end trace 2d6a9f6145e6cfab ]--- [ 24.993622] Kernel panic - not syncing: Fatal exception [ 24.999017] Dumping ftrace buffer: [ 25.002536] (ftrace buffer empty) [ 25.006226] Kernel Offset: disabled [ 25.009831] Rebooting in 86400 seconds..