[....] 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[ 14.850335] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.682616] random: sshd: uninitialized urandom read (32 bytes read) [ 19.987658] random: sshd: uninitialized urandom read (32 bytes read) [ 20.480032] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.51' (ECDSA) to the list of known hosts. [ 26.222390] urandom_read: 1 callbacks suppressed [ 26.222393] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.438441] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.446720] IP: [] l2tp_session_free+0x11c/0x200 [ 26.453137] PGD 1c4078067 [ 26.455780] PUD 1c1517067 PMD 0 [ 26.459258] [ 26.460886] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.465390] Dumping ftrace buffer: [ 26.468901] (ftrace buffer empty) [ 26.472586] Modules linked in: [ 26.475873] CPU: 1 PID: 3761 Comm: syz-executor781 Not tainted 4.9.124-g09eb2ba #83 [ 26.483636] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.493031] task: ffff8801bd831800 task.stack: ffff8801bbf80000 [ 26.499077] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.507945] RSP: 0018:ffff8801bbf87c98 EFLAGS: 00010246 [ 26.513367] RAX: dffffc0000000000 RBX: ffff8801bbe25680 RCX: 0000000000000000 [ 26.520708] RDX: 1ffff100393002b0 RSI: ffffffff836c4711 RDI: ffff8801c9801580 [ 26.527960] RBP: ffff8801bbf87cb8 R08: ffff8801bd8320e8 R09: 0000000000000000 [ 26.535209] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9801400 [ 26.542476] R13: ffff8801bbe25688 R14: 0000000000000000 R15: 0000000000000000 [ 26.549722] FS: 000000000220e880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.557926] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.563783] CR2: 0000000000000080 CR3: 00000001c4108000 CR4: 00000000001606f0 [ 26.571029] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.578280] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.585528] Stack: [ 26.587652] ffff8801bc386600 ffff8801bbe25680 ffff8801bc3869d0 ffff8801bc3868d8 [ 26.595643] ffff8801bbf87ce0 ffffffff836cc022 ffff8801bc386a40 ffff8801bc386600 [ 26.603653] ffffffff836cbf50 ffff8801bbf87d18 ffffffff830281f5 ffff8801bc386a40 [ 26.611750] Call Trace: [ 26.614328] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.620971] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.627367] [] __sk_destruct+0x55/0x590 [ 26.632968] [] sk_destruct+0x63/0x80 [ 26.638347] [] __sk_free+0x4f/0x220 [ 26.643604] [] sk_free+0x2b/0x40 [ 26.648597] [] pppol2tp_release+0x239/0x2e0 [ 26.654589] [] __sock_release+0xd7/0x260 [ 26.660280] [] ? __sock_release+0x260/0x260 [ 26.666227] [] sock_close+0x19/0x20 [ 26.671482] [] __fput+0x263/0x700 [ 26.676560] [] ____fput+0x15/0x20 [ 26.681671] [] task_work_run+0x10c/0x180 [ 26.687357] [] exit_to_usermode_loop+0xfc/0x120 [ 26.693659] [] do_syscall_64+0x364/0x490 [ 26.699346] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.706243] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 26.733304] RIP [] l2tp_session_free+0x11c/0x200 [ 26.739810] RSP [ 26.743407] CR2: 0000000000000080 [ 26.746926] ---[ end trace 58417a21e65c59f4 ]--- [ 26.751695] Kernel panic - not syncing: Fatal exception [ 26.757386] Dumping ftrace buffer: [ 26.760904] (ftrace buffer empty) [ 26.764585] Kernel Offset: disabled [ 26.768183] Rebooting in 86400 seconds..