[....] 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[ 16.902146] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.567579] random: sshd: uninitialized urandom read (32 bytes read) [ 18.843916] random: sshd: uninitialized urandom read (32 bytes read) [ 19.367823] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.53' (ECDSA) to the list of known hosts. [ 25.176144] urandom_read: 1 callbacks suppressed [ 25.176147] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.401755] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.410018] IP: [] l2tp_session_free+0x11c/0x200 [ 25.416479] PGD 1c61aa067 [ 25.419122] PUD 1c3004067 PMD 0 [ 25.422619] [ 25.424274] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.428757] Dumping ftrace buffer: [ 25.432273] (ftrace buffer empty) [ 25.435971] Modules linked in: [ 25.439267] CPU: 1 PID: 3782 Comm: syz-executor922 Not tainted 4.9.123-g8dd3fc2 #27 [ 25.447057] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.456389] task: ffff8801b9f19800 task.stack: ffff8801b8080000 [ 25.462424] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.471300] RSP: 0018:ffff8801b8087ca0 EFLAGS: 00010246 [ 25.476726] RAX: dffffc0000000000 RBX: ffff8801c9ab9680 RCX: 0000000000000000 [ 25.483974] RDX: 1ffff10037097210 RSI: ffffffff836c4991 RDI: ffff8801b84b9080 [ 25.491221] RBP: ffff8801b8087cc0 R08: ffff8801b9f1a0e8 R09: 0000000000000000 [ 25.498473] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b84b8f00 [ 25.505724] R13: ffff8801c9ab9688 R14: 0000000000000000 R15: ffffffff8301abe0 [ 25.512975] FS: 000000000176a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.521186] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.527052] CR2: 0000000000000080 CR3: 00000001cae6b000 CR4: 00000000001606f0 [ 25.534306] Stack: [ 25.536435] ffff8801b86d6e80 ffff8801c9ab9680 ffff8801b86d7250 ffff8801b86d7158 [ 25.544456] ffff8801b8087ce8 ffffffff836cc2a2 ffff8801b86d72c0 ffff8801b86d6e80 [ 25.552459] ffffffff836cc1d0 ffff8801b8087d20 ffffffff830280f5 ffff8801b86d72c0 [ 25.560470] Call Trace: [ 25.563057] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.569702] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.576010] [] __sk_destruct+0x55/0x590 [ 25.581619] [] ? sock_release+0x1c0/0x1c0 [ 25.587432] [] sk_destruct+0x63/0x80 [ 25.592844] [] __sk_free+0x4f/0x220 [ 25.598100] [] sk_free+0x2b/0x40 [ 25.603096] [] pppol2tp_release+0x239/0x2e0 [ 25.609076] [] sock_release+0x96/0x1c0 [ 25.614606] [] sock_close+0x16/0x20 [ 25.619867] [] __fput+0x263/0x700 [ 25.624968] [] ____fput+0x15/0x20 [ 25.630054] [] task_work_run+0x10c/0x180 [ 25.635749] [] exit_to_usermode_loop+0xfc/0x120 [ 25.642054] [] do_syscall_64+0x364/0x490 [ 25.647747] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.654788] 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 c3 c9 fd 4c 89 ea 48 b8 00 [ 25.681968] RIP [] l2tp_session_free+0x11c/0x200 [ 25.688491] RSP [ 25.692092] CR2: 0000000000000080 [ 25.695775] ---[ end trace 3754bd08bb0a4d9e ]--- [ 25.700613] Kernel panic - not syncing: Fatal exception [ 25.706242] Dumping ftrace buffer: [ 25.709822] (ftrace buffer empty) [ 25.713573] Kernel Offset: disabled [ 25.717183] Rebooting in 86400 seconds..