[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.408319] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.470440] random: sshd: uninitialized urandom read (32 bytes read) [ 17.786402] random: sshd: uninitialized urandom read (32 bytes read) [ 18.328802] random: sshd: uninitialized urandom read (32 bytes read) [ 23.369830] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.12' (ECDSA) to the list of known hosts. [ 28.963648] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.164628] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.172861] IP: [] l2tp_session_free+0x11c/0x200 [ 29.179286] PGD 1be722067 [ 29.181932] PUD 1bd40d067 PMD 0 [ 29.185421] [ 29.187044] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.191512] Dumping ftrace buffer: [ 29.195028] (ftrace buffer empty) [ 29.198718] Modules linked in: [ 29.202010] CPU: 0 PID: 3799 Comm: syz-executor843 Not tainted 4.9.123-g8dd3fc2 #27 [ 29.209780] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.219125] task: ffff8801b8819800 task.stack: ffff8801d90f8000 [ 29.225338] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 29.234452] RSP: 0018:ffff8801d90ffca0 EFLAGS: 00010246 [ 29.239947] RAX: dffffc0000000000 RBX: ffff8801b7000280 RCX: 0000000000000000 [ 29.247229] RDX: 1ffff10039210700 RSI: ffffffff836c4991 RDI: ffff8801c9083800 [ 29.254486] RBP: ffff8801d90ffcc0 R08: ffff8801b881a0e8 R09: 0000000000000000 [ 29.261755] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9083680 [ 29.269013] R13: ffff8801b7000288 R14: 0000000000000000 R15: ffffffff8301abe0 [ 29.276264] FS: 0000000000c03880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 29.284474] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.290396] CR2: 0000000000000080 CR3: 00000001b6887000 CR4: 00000000001606f0 [ 29.297657] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 29.304905] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 29.312154] Stack: [ 29.314293] ffff8801b87c8880 ffff8801b7000280 ffff8801b87c8c50 ffff8801b87c8b58 [ 29.322286] ffff8801d90ffce8 ffffffff836cc2a2 ffff8801b87c8cc0 ffff8801b87c8880 [ 29.330287] ffffffff836cc1d0 ffff8801d90ffd20 ffffffff830280f5 ffff8801b87c8cc0 [ 29.338282] Call Trace: [ 29.340848] [] pppol2tp_session_destruct+0xd2/0x110 [ 29.347496] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 29.353868] [] __sk_destruct+0x55/0x590 [ 29.359479] [] ? sock_release+0x1c0/0x1c0 [ 29.365256] [] sk_destruct+0x63/0x80 [ 29.370604] [] __sk_free+0x4f/0x220 [ 29.375858] [] sk_free+0x2b/0x40 [ 29.380853] [] pppol2tp_release+0x239/0x2e0 [ 29.386806] [] sock_release+0x96/0x1c0 [ 29.392383] [] sock_close+0x16/0x20 [ 29.397649] [] __fput+0x263/0x700 [ 29.402736] [] ____fput+0x15/0x20 [ 29.407820] [] task_work_run+0x10c/0x180 [ 29.413517] [] exit_to_usermode_loop+0xfc/0x120 [ 29.419823] [] do_syscall_64+0x364/0x490 [ 29.425523] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.432482] 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 [ 29.459373] RIP [] l2tp_session_free+0x11c/0x200 [ 29.466014] RSP [ 29.469620] CR2: 0000000000000080 [ 29.473516] ---[ end trace 9b2d5e2dbc603993 ]--- [ 29.478311] Kernel panic - not syncing: Fatal exception [ 29.483995] Dumping ftrace buffer: [ 29.487524] (ftrace buffer empty) [ 29.491208] Kernel Offset: disabled [ 29.494814] Rebooting in 86400 seconds..