[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.733049] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 15.624910] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.020453] random: sshd: uninitialized urandom read (32 bytes read) [ 16.560843] random: sshd: uninitialized urandom read (32 bytes read) [ 16.699702] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.23' (ECDSA) to the list of known hosts. [ 22.368366] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.505760] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.514021] IP: [] l2tp_session_free+0x11c/0x200 [ 22.520464] PGD 1bd8d4067 [ 22.523110] PUD 1bb88f067 PMD 0 [ 22.526587] [ 22.528209] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.532687] Dumping ftrace buffer: [ 22.536200] (ftrace buffer empty) [ 22.539888] Modules linked in: [ 22.543188] CPU: 0 PID: 3792 Comm: syz-executor998 Not tainted 4.9.123-g8dd3fc2 #79 [ 22.550964] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.560295] task: ffff8801b7a0e000 task.stack: ffff8801b61a8000 [ 22.566322] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.575178] RSP: 0018:ffff8801b61afca0 EFLAGS: 00010246 [ 22.580603] RAX: dffffc0000000000 RBX: ffff8801cb619400 RCX: 0000000000000000 [ 22.587851] RDX: 1ffff10039696f50 RSI: ffffffff836c4991 RDI: ffff8801cb4b7a80 [ 22.595096] RBP: ffff8801b61afcc0 R08: ffff8801b7a0e8e8 R09: 0000000000000000 [ 22.602347] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb4b7900 [ 22.609592] R13: ffff8801cb619408 R14: 0000000000000000 R15: ffffffff8301abe0 [ 22.616838] FS: 00000000011dc880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 22.625040] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.630896] CR2: 0000000000000080 CR3: 00000001bd887000 CR4: 00000000001606f0 [ 22.638145] Stack: [ 22.640273] ffff8801b7e26e80 ffff8801cb619400 ffff8801b7e27250 ffff8801b7e27158 [ 22.648270] ffff8801b61afce8 ffffffff836cc2a2 ffff8801b7e272c0 ffff8801b7e26e80 [ 22.656292] ffffffff836cc1d0 ffff8801b61afd20 ffffffff830280f5 ffff8801b7e272c0 [ 22.664294] Call Trace: [ 22.666859] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.673515] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.679828] [] __sk_destruct+0x55/0x590 [ 22.686211] [] ? sock_release+0x1c0/0x1c0 [ 22.691987] [] sk_destruct+0x63/0x80 [ 22.697324] [] __sk_free+0x4f/0x220 [ 22.702576] [] sk_free+0x2b/0x40 [ 22.707574] [] pppol2tp_release+0x239/0x2e0 [ 22.713519] [] sock_release+0x96/0x1c0 [ 22.719051] [] sock_close+0x16/0x20 [ 22.724314] [] __fput+0x263/0x700 [ 22.729393] [] ____fput+0x15/0x20 [ 22.734474] [] task_work_run+0x10c/0x180 [ 22.740161] [] exit_to_usermode_loop+0xfc/0x120 [ 22.746457] [] do_syscall_64+0x364/0x490 [ 22.752144] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.759047] 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 [ 22.786167] RIP [] l2tp_session_free+0x11c/0x200 [ 22.792688] RSP [ 22.796286] CR2: 0000000000000080 [ 22.800014] ---[ end trace 2acb9c498d25d452 ]--- [ 22.804767] Kernel panic - not syncing: Fatal exception [ 22.810449] Dumping ftrace buffer: [ 22.813969] (ftrace buffer empty) [ 22.817651] Kernel Offset: disabled [ 22.821261] Rebooting in 86400 seconds..