[....] 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[ 13.043904] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.360918] random: sshd: uninitialized urandom read (32 bytes read) [ 27.819191] random: sshd: uninitialized urandom read (32 bytes read) [ 28.234483] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.32' (ECDSA) to the list of known hosts. [ 33.806606] urandom_read: 1 callbacks suppressed [ 33.806609] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.027385] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.035617] IP: [] l2tp_session_free+0x11c/0x200 [ 34.042037] PGD 1c76c7067 [ 34.044692] PUD 1c9f42067 PMD 0 [ 34.048167] [ 34.049788] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.054253] Dumping ftrace buffer: [ 34.057765] (ftrace buffer empty) [ 34.061446] Modules linked in: [ 34.064742] CPU: 1 PID: 3814 Comm: syz-executor583 Not tainted 4.9.118-g47b77b8 #20 [ 34.072507] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.081834] task: ffff8801b72e4800 task.stack: ffff8801b5a68000 [ 34.087869] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.096715] RSP: 0018:ffff8801b5a6fca0 EFLAGS: 00010246 [ 34.102146] RAX: dffffc0000000000 RBX: ffff8801b58e6000 RCX: 0000000000000000 [ 34.109399] RDX: 1ffff10036bea830 RSI: ffffffff836bf781 RDI: ffff8801b5f54180 [ 34.116643] RBP: ffff8801b5a6fcc0 R08: ffff8801b72e50e8 R09: 0000000000000000 [ 34.123883] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5f54000 [ 34.131124] R13: ffff8801b58e6008 R14: 0000000000000000 R15: ffffffff83015be0 [ 34.138370] FS: 000000000269b880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 34.146569] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.152436] CR2: 0000000000000080 CR3: 00000001c82d7000 CR4: 00000000001606f0 [ 34.159682] Stack: [ 34.161803] ffff8801b5cfee80 ffff8801b58e6000 ffff8801b5cff250 ffff8801b5cff158 [ 34.169804] ffff8801b5a6fce8 ffffffff836c7092 ffff8801b5cff2c0 ffff8801b5cfee80 [ 34.177813] ffffffff836c6fc0 ffff8801b5a6fd20 ffffffff830230f5 ffff8801b5cff2c0 [ 34.185801] Call Trace: [ 34.188375] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.195017] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.201312] [] __sk_destruct+0x55/0x590 [ 34.206913] [] ? sock_release+0x1c0/0x1c0 [ 34.212683] [] sk_destruct+0x63/0x80 [ 34.218020] [] __sk_free+0x4f/0x220 [ 34.223289] [] sk_free+0x2b/0x40 [ 34.228279] [] pppol2tp_release+0x239/0x2e0 [ 34.234221] [] sock_release+0x96/0x1c0 [ 34.239753] [] sock_close+0x16/0x20 [ 34.245002] [] __fput+0x263/0x700 [ 34.250094] [] ____fput+0x15/0x20 [ 34.255187] [] task_work_run+0x10c/0x180 [ 34.260882] [] exit_to_usermode_loop+0xfc/0x120 [ 34.267173] [] do_syscall_64+0x364/0x490 [ 34.272863] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.279758] 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 [ 34.306656] RIP [] l2tp_session_free+0x11c/0x200 [ 34.313156] RSP [ 34.316767] CR2: 0000000000000080 [ 34.320391] ---[ end trace 5c1ffa7bf2025612 ]--- [ 34.325135] Kernel panic - not syncing: Fatal exception [ 34.330732] Dumping ftrace buffer: [ 34.334249] (ftrace buffer empty) [ 34.337934] Kernel Offset: disabled [ 34.341545] Rebooting in 86400 seconds..