[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.768474] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.242437] random: sshd: uninitialized urandom read (32 bytes read) [ 27.553876] random: sshd: uninitialized urandom read (32 bytes read) [ 28.182094] random: sshd: uninitialized urandom read (32 bytes read) [ 41.673060] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.15' (ECDSA) to the list of known hosts. [ 47.043080] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 47.243890] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 47.252115] IP: [] l2tp_session_free+0x11c/0x200 [ 47.258542] PGD 1c0264067 [ 47.261220] PUD 1c0265067 PMD 0 [ 47.264734] [ 47.266354] Oops: 0002 [#1] PREEMPT SMP KASAN [ 47.270823] Dumping ftrace buffer: [ 47.274340] (ftrace buffer empty) [ 47.279916] Modules linked in: [ 47.283207] CPU: 1 PID: 3778 Comm: syz-executor104 Not tainted 4.9.113-g9905591 #14 [ 47.291739] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.301189] task: ffff8801be71e000 task.stack: ffff8801bb0c8000 [ 47.307220] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 47.316075] RSP: 0018:ffff8801bb0cfca0 EFLAGS: 00010246 [ 47.321509] RAX: dffffc0000000000 RBX: ffff8801bb4aca00 RCX: 0000000000000000 [ 47.329868] RDX: 1ffff100377d80d0 RSI: ffffffff836bcee1 RDI: ffff8801bbec0680 [ 47.337840] RBP: ffff8801bb0cfcc0 R08: ffff8801be71e8e8 R09: 0000000000000000 [ 47.345106] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bbec0500 [ 47.353844] R13: ffff8801bb4aca08 R14: 0000000000000000 R15: ffffffff83013be0 [ 47.361104] FS: 000000000195a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 47.369315] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 47.375180] CR2: 0000000000000080 CR3: 00000001bd415000 CR4: 00000000001606f0 [ 47.382438] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 47.389697] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 47.396955] Stack: [ 47.399090] ffff8801bbe25d80 ffff8801bb4aca00 ffff8801bbe26150 ffff8801bbe26058 [ 47.407119] ffff8801bb0cfce8 ffffffff836c47f2 ffff8801bbe261c0 ffff8801bbe25d80 [ 47.415152] ffffffff836c4720 ffff8801bb0cfd20 ffffffff83021095 ffff8801bbe261c0 [ 47.423175] Call Trace: [ 47.425758] [] pppol2tp_session_destruct+0xd2/0x110 [ 47.432417] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 47.438759] [] __sk_destruct+0x55/0x590 [ 47.444375] [] ? sock_release+0x1c0/0x1c0 [ 47.450160] [] sk_destruct+0x63/0x80 [ 47.456044] [] __sk_free+0x4f/0x220 [ 47.461311] [] sk_free+0x2b/0x40 [ 47.466316] [] pppol2tp_release+0x239/0x2e0 [ 47.472276] [] sock_release+0x96/0x1c0 [ 47.477804] [] sock_close+0x16/0x20 [ 47.483073] [] __fput+0x263/0x700 [ 47.488165] [] ____fput+0x15/0x20 [ 47.493287] [] task_work_run+0x10c/0x180 [ 47.498992] [] exit_to_usermode_loop+0xfc/0x120 [ 47.505912] [] do_syscall_64+0x364/0x490 [ 47.511621] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 47.518533] 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 1b ca fd 4c 89 ea 48 b8 00 [ 47.545933] RIP [] l2tp_session_free+0x11c/0x200 [ 47.552463] RSP [ 47.556074] CR2: 0000000000000080 [ 47.560966] ---[ end trace 7db4e7b5a045cc65 ]--- [ 47.565760] Kernel panic - not syncing: Fatal exception [ 47.572381] Dumping ftrace buffer: [ 47.575915] (ftrace buffer empty) [ 47.579617] Kernel Offset: disabled [ 47.583236] Rebooting in 86400 seconds..