[....] 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[ 16.183900] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.611791] random: sshd: uninitialized urandom read (32 bytes read) [ 17.881009] random: sshd: uninitialized urandom read (32 bytes read) [ 18.367493] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.48' (ECDSA) to the list of known hosts. [ 24.012160] urandom_read: 1 callbacks suppressed [ 24.012163] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.219515] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.227761] IP: [] l2tp_session_free+0x11c/0x200 [ 24.234194] PGD 1c0c7d067 [ 24.236837] PUD 1c4f05067 PMD 0 [ 24.240390] [ 24.242028] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.246498] Dumping ftrace buffer: [ 24.250008] (ftrace buffer empty) [ 24.253691] Modules linked in: [ 24.256997] CPU: 1 PID: 3797 Comm: syz-executor915 Not tainted 4.9.122-g54068d6 #78 [ 24.264766] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.274093] task: ffff8801b87fb000 task.stack: ffff8801b7048000 [ 24.280133] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.288993] RSP: 0018:ffff8801b704fca0 EFLAGS: 00010246 [ 24.294414] RAX: dffffc0000000000 RBX: ffff8801cb40b680 RCX: 0000000000000000 [ 24.301746] RDX: 1ffff100396195c0 RSI: ffffffff836c39a1 RDI: ffff8801cb0cae00 [ 24.308993] RBP: ffff8801b704fcc0 R08: ffff8801b87fb8e8 R09: 0000000000000000 [ 24.316248] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb0cac80 [ 24.323490] R13: ffff8801cb40b688 R14: 0000000000000000 R15: ffffffff83019be0 [ 24.330748] FS: 0000000000f23880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 24.338946] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.344801] CR2: 0000000000000080 CR3: 00000001c8c28000 CR4: 00000000001606f0 [ 24.352047] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.359290] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.366533] Stack: [ 24.368656] ffff8801b768a200 ffff8801cb40b680 ffff8801b768a5d0 ffff8801b768a4d8 [ 24.376659] ffff8801b704fce8 ffffffff836cb2b2 ffff8801b768a640 ffff8801b768a200 [ 24.384711] ffffffff836cb1e0 ffff8801b704fd20 ffffffff830270f5 ffff8801b768a640 [ 24.392752] Call Trace: [ 24.395322] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.401964] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.408259] [] __sk_destruct+0x55/0x590 [ 24.413874] [] ? sock_release+0x1c0/0x1c0 [ 24.419663] [] sk_destruct+0x63/0x80 [ 24.425031] [] __sk_free+0x4f/0x220 [ 24.430299] [] sk_free+0x2b/0x40 [ 24.435293] [] pppol2tp_release+0x239/0x2e0 [ 24.441250] [] sock_release+0x96/0x1c0 [ 24.446761] [] sock_close+0x16/0x20 [ 24.452032] [] __fput+0x263/0x700 [ 24.457110] [] ____fput+0x15/0x20 [ 24.462202] [] task_work_run+0x10c/0x180 [ 24.467899] [] exit_to_usermode_loop+0xfc/0x120 [ 24.474197] [] do_syscall_64+0x364/0x490 [ 24.479910] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.486831] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 24.514065] RIP [] l2tp_session_free+0x11c/0x200 [ 24.520598] RSP [ 24.524200] CR2: 0000000000000080 [ 24.527961] ---[ end trace ed4ebcb6c3bdb0f4 ]--- [ 24.532727] Kernel panic - not syncing: Fatal exception [ 24.538422] Dumping ftrace buffer: [ 24.541940] (ftrace buffer empty) [ 24.545623] Kernel Offset: disabled [ 24.549236] Rebooting in 86400 seconds..