[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.579638] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.605296] random: sshd: uninitialized urandom read (32 bytes read) [ 20.058001] random: sshd: uninitialized urandom read (32 bytes read) [ 20.971822] random: sshd: uninitialized urandom read (32 bytes read) [ 21.107614] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.8' (ECDSA) to the list of known hosts. [ 26.562606] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.786753] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.795005] IP: [] l2tp_session_free+0x11c/0x200 [ 26.801447] PGD 1c69ac067 [ 26.804088] PUD 1c693d067 PMD 0 [ 26.807578] [ 26.809197] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.813665] Dumping ftrace buffer: [ 26.817176] (ftrace buffer empty) [ 26.820858] Modules linked in: [ 26.824168] CPU: 0 PID: 3801 Comm: syz-executor049 Not tainted 4.9.113-g47bbcd6 #62 [ 26.831943] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.841358] task: ffff8801b6f13000 task.stack: ffff8801b59b8000 [ 26.847488] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.856331] RSP: 0018:ffff8801b59bfca0 EFLAGS: 00010246 [ 26.861752] RAX: dffffc0000000000 RBX: ffff8801cb1bb680 RCX: 0000000000000000 [ 26.869001] RDX: 1ffff100396673a0 RSI: ffffffff836bcce1 RDI: ffff8801cb339d00 [ 26.876244] RBP: ffff8801b59bfcc0 R08: ffff8801b6f138e8 R09: 0000000000000000 [ 26.883496] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb339b80 [ 26.890738] R13: ffff8801cb1bb688 R14: 0000000000000000 R15: ffffffff83013be0 [ 26.897985] FS: 00000000017da880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 26.906182] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.912060] CR2: 0000000000000080 CR3: 00000001b9ecf000 CR4: 00000000001606f0 [ 26.919317] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.926561] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.933802] Stack: [ 26.935923] ffff8801b5c2dd80 ffff8801cb1bb680 ffff8801b5c2e150 ffff8801b5c2e058 [ 26.943914] ffff8801b59bfce8 ffffffff836c45f2 ffff8801b5c2e1c0 ffff8801b5c2dd80 [ 26.951900] ffffffff836c4520 ffff8801b59bfd20 ffffffff83021095 ffff8801b5c2e1c0 [ 26.959900] Call Trace: [ 26.962466] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.969112] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.975405] [] __sk_destruct+0x55/0x590 [ 26.981002] [] ? sock_release+0x1c0/0x1c0 [ 26.986781] [] sk_destruct+0x63/0x80 [ 26.992126] [] __sk_free+0x4f/0x220 [ 26.997374] [] sk_free+0x2b/0x40 [ 27.002361] [] pppol2tp_release+0x239/0x2e0 [ 27.008313] [] sock_release+0x96/0x1c0 [ 27.013827] [] sock_close+0x16/0x20 [ 27.019085] [] __fput+0x263/0x700 [ 27.024161] [] ____fput+0x15/0x20 [ 27.029240] [] task_work_run+0x10c/0x180 [ 27.034922] [] exit_to_usermode_loop+0xfc/0x120 [ 27.041212] [] do_syscall_64+0x364/0x490 [ 27.046896] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.054051] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 27.080963] RIP [] l2tp_session_free+0x11c/0x200 [ 27.087468] RSP [ 27.091063] CR2: 0000000000000080 [ 27.095309] ---[ end trace 0a4c0e2c80feb79f ]--- [ 27.100107] Kernel panic - not syncing: Fatal exception [ 27.105884] Dumping ftrace buffer: [ 27.109402] (ftrace buffer empty) [ 27.113091] Kernel Offset: disabled [ 27.116701] Rebooting in 86400 seconds..