[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.208240] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.826880] random: sshd: uninitialized urandom read (32 bytes read) [ 22.052767] random: sshd: uninitialized urandom read (32 bytes read) [ 22.585629] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.15' (ECDSA) to the list of known hosts. [ 28.084148] urandom_read: 1 callbacks suppressed [ 28.084151] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.306824] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.315051] IP: [] l2tp_session_free+0x11c/0x200 [ 28.321471] PGD 1c4080067 [ 28.324111] PUD 1c408a067 PMD 0 [ 28.327589] [ 28.329236] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.333714] Dumping ftrace buffer: [ 28.337226] (ftrace buffer empty) [ 28.340911] Modules linked in: [ 28.344199] CPU: 0 PID: 3788 Comm: syz-executor017 Not tainted 4.9.117-g8b21e85 #71 [ 28.351963] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.361321] task: ffff8801b87b9800 task.stack: ffff8801b87a0000 [ 28.367346] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.376202] RSP: 0018:ffff8801b87a7ca0 EFLAGS: 00010246 [ 28.381620] RAX: dffffc0000000000 RBX: ffff8801b81a9180 RCX: 0000000000000000 [ 28.388862] RDX: 1ffff100393002b0 RSI: ffffffff836bf8f1 RDI: ffff8801c9801580 [ 28.396100] RBP: ffff8801b87a7cc0 R08: ffff8801b87ba0e8 R09: 0000000000000000 [ 28.403340] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9801400 [ 28.410582] R13: ffff8801b81a9188 R14: 0000000000000000 R15: ffffffff83015be0 [ 28.417823] FS: 0000000002126880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 28.426019] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.431872] CR2: 0000000000000080 CR3: 00000001c6f01000 CR4: 00000000001606f0 [ 28.439127] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.446372] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.453615] Stack: [ 28.455737] ffff8801b7ef5500 ffff8801b81a9180 ffff8801b7ef58d0 ffff8801b7ef57d8 [ 28.463723] ffff8801b87a7ce8 ffffffff836c7202 ffff8801b7ef5940 ffff8801b7ef5500 [ 28.471727] ffffffff836c7130 ffff8801b87a7d20 ffffffff83023095 ffff8801b7ef5940 [ 28.479713] Call Trace: [ 28.482276] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.488936] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.495225] [] __sk_destruct+0x55/0x590 [ 28.500821] [] ? sock_release+0x1c0/0x1c0 [ 28.506694] [] sk_destruct+0x63/0x80 [ 28.512027] [] __sk_free+0x4f/0x220 [ 28.517274] [] sk_free+0x2b/0x40 [ 28.522273] [] pppol2tp_release+0x239/0x2e0 [ 28.528244] [] sock_release+0x96/0x1c0 [ 28.533766] [] sock_close+0x16/0x20 [ 28.539020] [] __fput+0x263/0x700 [ 28.544097] [] ____fput+0x15/0x20 [ 28.549175] [] task_work_run+0x10c/0x180 [ 28.554860] [] exit_to_usermode_loop+0xfc/0x120 [ 28.561151] [] do_syscall_64+0x364/0x490 [ 28.566839] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.573757] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 28.600708] RIP [] l2tp_session_free+0x11c/0x200 [ 28.607231] RSP [ 28.610827] CR2: 0000000000000080 [ 28.615641] ---[ end trace 13538973bcda5a80 ]--- [ 28.620396] Kernel panic - not syncing: Fatal exception [ 28.626066] Dumping ftrace buffer: [ 28.629579] (ftrace buffer empty) [ 28.633263] Kernel Offset: disabled [ 28.636860] Rebooting in 86400 seconds..