[....] 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[ 12.459044] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.638495] random: sshd: uninitialized urandom read (32 bytes read) [ 28.928033] random: sshd: uninitialized urandom read (32 bytes read) [ 29.283664] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.45' (ECDSA) to the list of known hosts. [ 34.874568] urandom_read: 1 callbacks suppressed [ 34.874571] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 35.067064] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 35.075275] IP: [] l2tp_session_free+0x11c/0x200 [ 35.081691] PGD 1c82d4067 [ 35.084332] PUD 1c9174067 PMD 0 [ 35.087801] [ 35.089418] Oops: 0002 [#1] PREEMPT SMP KASAN [ 35.093891] Dumping ftrace buffer: [ 35.097412] (ftrace buffer empty) [ 35.101094] Modules linked in: [ 35.104380] CPU: 1 PID: 3805 Comm: syz-executor524 Not tainted 4.9.117-g8b21e85 #19 [ 35.112147] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.121475] task: ffff8801b8948000 task.stack: ffff8801b6c78000 [ 35.127504] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 35.136347] RSP: 0018:ffff8801b6c7fca0 EFLAGS: 00010246 [ 35.141766] RAX: dffffc0000000000 RBX: ffff8801b96eea00 RCX: 0000000000000000 [ 35.149009] RDX: 1ffff10036ed5d70 RSI: ffffffff836bf8f1 RDI: ffff8801b76aeb80 [ 35.156248] RBP: ffff8801b6c7fcc0 R08: ffff8801b89488e8 R09: 0000000000000000 [ 35.163488] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b76aea00 [ 35.170739] R13: ffff8801b96eea08 R14: 0000000000000000 R15: ffffffff83015be0 [ 35.177983] FS: 0000000001eda880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 35.186179] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.192040] CR2: 0000000000000080 CR3: 00000001c9290000 CR4: 00000000001606f0 [ 35.199284] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 35.206527] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 35.213765] Stack: [ 35.215887] ffff8801d946cc80 ffff8801b96eea00 ffff8801d946d050 ffff8801d946cf58 [ 35.223869] ffff8801b6c7fce8 ffffffff836c7202 ffff8801d946d0c0 ffff8801d946cc80 [ 35.231855] ffffffff836c7130 ffff8801b6c7fd20 ffffffff83023095 ffff8801d946d0c0 [ 35.239852] Call Trace: [ 35.242415] [] pppol2tp_session_destruct+0xd2/0x110 [ 35.249050] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.255343] [] __sk_destruct+0x55/0x590 [ 35.260940] [] ? sock_release+0x1c0/0x1c0 [ 35.266707] [] sk_destruct+0x63/0x80 [ 35.272040] [] __sk_free+0x4f/0x220 [ 35.277284] [] sk_free+0x2b/0x40 [ 35.282287] [] pppol2tp_release+0x239/0x2e0 [ 35.288232] [] sock_release+0x96/0x1c0 [ 35.293738] [] sock_close+0x16/0x20 [ 35.298988] [] __fput+0x263/0x700 [ 35.304062] [] ____fput+0x15/0x20 [ 35.309135] [] task_work_run+0x10c/0x180 [ 35.314817] [] exit_to_usermode_loop+0xfc/0x120 [ 35.321107] [] do_syscall_64+0x364/0x490 [ 35.326790] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.333692] 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 [ 35.360497] RIP [] l2tp_session_free+0x11c/0x200 [ 35.367012] RSP [ 35.370621] CR2: 0000000000000080 [ 35.374277] ---[ end trace 6437c373081c05e1 ]--- [ 35.379030] Kernel panic - not syncing: Fatal exception [ 35.384755] Dumping ftrace buffer: [ 35.388267] (ftrace buffer empty) [ 35.391948] Kernel Offset: disabled [ 35.395546] Rebooting in 86400 seconds..