[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.373602] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.394447] random: sshd: uninitialized urandom read (32 bytes read) [ 15.854686] random: sshd: uninitialized urandom read (32 bytes read) [ 16.833298] random: sshd: uninitialized urandom read (32 bytes read) [ 16.973823] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.63' (ECDSA) to the list of known hosts. [ 22.412116] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.611223] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.619482] IP: [] l2tp_session_free+0x11c/0x200 [ 22.625921] PGD 1b9b86067 [ 22.628564] PUD 1b7aab067 PMD 0 [ 22.632048] [ 22.633668] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.638149] Dumping ftrace buffer: [ 22.641663] (ftrace buffer empty) [ 22.645349] Modules linked in: [ 22.648667] CPU: 1 PID: 3795 Comm: syz-executor242 Not tainted 4.9.113-g47bbcd6 #62 [ 22.656438] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.665786] task: ffff8801b7078000 task.stack: ffff8801b5c10000 [ 22.671971] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.680837] RSP: 0018:ffff8801b5c17ca0 EFLAGS: 00010246 [ 22.686285] RAX: dffffc0000000000 RBX: ffff8801b6228280 RCX: 0000000000000000 [ 22.693532] RDX: 1ffff10036c64700 RSI: ffffffff836bcce1 RDI: ffff8801b6323800 [ 22.700783] RBP: ffff8801b5c17cc0 R08: ffff8801b70788e8 R09: 0000000000000000 [ 22.708027] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6323680 [ 22.715270] R13: ffff8801b6228288 R14: 0000000000000000 R15: ffffffff83013be0 [ 22.722517] FS: 00000000024b6880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 22.730730] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.736588] CR2: 0000000000000080 CR3: 00000001c225b000 CR4: 00000000001606f0 [ 22.743839] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 22.751097] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 22.758342] Stack: [ 22.760470] ffff8801b648c400 ffff8801b6228280 ffff8801b648c7d0 ffff8801b648c6d8 [ 22.768470] ffff8801b5c17ce8 ffffffff836c45f2 ffff8801b648c840 ffff8801b648c400 [ 22.777088] ffffffff836c4520 ffff8801b5c17d20 ffffffff83021095 ffff8801b648c840 [ 22.785077] Call Trace: [ 22.787647] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.794290] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.800582] [] __sk_destruct+0x55/0x590 [ 22.806182] [] ? sock_release+0x1c0/0x1c0 [ 22.811953] [] sk_destruct+0x63/0x80 [ 22.817292] [] __sk_free+0x4f/0x220 [ 22.822542] [] sk_free+0x2b/0x40 [ 22.827532] [] pppol2tp_release+0x239/0x2e0 [ 22.833491] [] sock_release+0x96/0x1c0 [ 22.839019] [] sock_close+0x16/0x20 [ 22.844298] [] __fput+0x263/0x700 [ 22.849384] [] ____fput+0x15/0x20 [ 22.854480] [] task_work_run+0x10c/0x180 [ 22.860174] [] exit_to_usermode_loop+0xfc/0x120 [ 22.866481] [] do_syscall_64+0x364/0x490 [ 22.872169] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.879063] 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 [ 22.905993] RIP [] l2tp_session_free+0x11c/0x200 [ 22.912501] RSP [ 22.916099] CR2: 0000000000000080 [ 22.919611] ---[ end trace ecdb5f4356dc6cc6 ]--- [ 22.924391] Kernel panic - not syncing: Fatal exception [ 22.930213] Dumping ftrace buffer: [ 22.933735] (ftrace buffer empty) [ 22.937418] Kernel Offset: disabled [ 22.941034] Rebooting in 86400 seconds..