[....] 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[ 12.049183] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.162576] random: sshd: uninitialized urandom read (32 bytes read) [ 18.473196] random: sshd: uninitialized urandom read (32 bytes read) [ 18.981487] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.8' (ECDSA) to the list of known hosts. [ 24.787473] urandom_read: 1 callbacks suppressed [ 24.787477] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.995573] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.003807] IP: [] l2tp_session_free+0x11c/0x200 [ 25.010258] PGD 1c4234067 [ 25.012906] PUD 1c5116067 PMD 0 [ 25.016390] [ 25.018034] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.022506] Dumping ftrace buffer: [ 25.026025] (ftrace buffer empty) [ 25.029715] Modules linked in: [ 25.033071] CPU: 0 PID: 3748 Comm: syz-executor153 Not tainted 4.9.120-gf85543b #76 [ 25.040836] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.050177] task: ffff8801bf0de000 task.stack: ffff8801bcd28000 [ 25.056207] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.065068] RSP: 0018:ffff8801bcd2fca0 EFLAGS: 00010246 [ 25.070498] RAX: dffffc0000000000 RBX: ffff8801bcc88c80 RCX: 0000000000000000 [ 25.077743] RDX: 1ffff1003925b520 RSI: ffffffff836c29a1 RDI: ffff8801c92da900 [ 25.084988] RBP: ffff8801bcd2fcc0 R08: ffff8801bf0de8e8 R09: 0000000000000000 [ 25.092237] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c92da780 [ 25.099491] R13: ffff8801bcc88c88 R14: 0000000000000000 R15: ffffffff83018be0 [ 25.106750] FS: 0000000001229880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.114957] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.120817] CR2: 0000000000000080 CR3: 00000001c7929000 CR4: 00000000001606f0 [ 25.128074] Stack: [ 25.130219] ffff8801c9f6bb80 ffff8801bcc88c80 ffff8801c9f6bf50 ffff8801c9f6be58 [ 25.138282] ffff8801bcd2fce8 ffffffff836ca2b2 ffff8801c9f6bfc0 ffff8801c9f6bb80 [ 25.146285] ffffffff836ca1e0 ffff8801bcd2fd20 ffffffff830260f5 ffff8801c9f6bfc0 [ 25.154274] Call Trace: [ 25.156845] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.163491] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.169795] [] __sk_destruct+0x55/0x590 [ 25.175406] [] ? sock_release+0x1c0/0x1c0 [ 25.181183] [] sk_destruct+0x63/0x80 [ 25.186523] [] __sk_free+0x4f/0x220 [ 25.191772] [] sk_free+0x2b/0x40 [ 25.196762] [] pppol2tp_release+0x239/0x2e0 [ 25.202715] [] sock_release+0x96/0x1c0 [ 25.208233] [] sock_close+0x16/0x20 [ 25.213492] [] __fput+0x263/0x700 [ 25.218588] [] ____fput+0x15/0x20 [ 25.223671] [] task_work_run+0x10c/0x180 [ 25.229361] [] exit_to_usermode_loop+0xfc/0x120 [ 25.235657] [] do_syscall_64+0x364/0x490 [ 25.241347] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.248243] 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 15 de c9 fd 4c 89 ea 48 b8 00 [ 25.275184] RIP [] l2tp_session_free+0x11c/0x200 [ 25.281789] RSP [ 25.285389] CR2: 0000000000000080 [ 25.289167] ---[ end trace ab029331293fedc9 ]--- [ 25.293981] Kernel panic - not syncing: Fatal exception [ 25.299626] Dumping ftrace buffer: [ 25.303148] (ftrace buffer empty) [ 25.306835] Kernel Offset: disabled [ 25.310436] Rebooting in 86400 seconds..