[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.618857] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 29.726263] random: sshd: uninitialized urandom read (32 bytes read) [ 30.133683] random: sshd: uninitialized urandom read (32 bytes read) [ 30.797263] random: sshd: uninitialized urandom read (32 bytes read) [ 30.909288] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.28' (ECDSA) to the list of known hosts. [ 36.291410] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 36.492156] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 36.500374] IP: [] l2tp_session_free+0x11c/0x200 [ 36.506805] PGD 1b643a067 [ 36.509445] PUD 1b643b067 PMD 0 [ 36.512917] [ 36.514535] Oops: 0002 [#1] PREEMPT SMP KASAN [ 36.519003] Dumping ftrace buffer: [ 36.522511] (ftrace buffer empty) [ 36.526193] Modules linked in: [ 36.529477] CPU: 1 PID: 3807 Comm: syz-executor932 Not tainted 4.9.113-g47bbcd6 #62 [ 36.537237] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.546562] task: ffff8801caf73000 task.stack: ffff8801d9be0000 [ 36.552588] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 36.561444] RSP: 0018:ffff8801d9be7ca0 EFLAGS: 00010246 [ 36.566864] RAX: dffffc0000000000 RBX: ffff8801cb518000 RCX: 0000000000000000 [ 36.574106] RDX: 1ffff10036ea8120 RSI: ffffffff836bcce1 RDI: ffff8801b7540900 [ 36.581347] RBP: ffff8801d9be7cc0 R08: ffff8801caf738e8 R09: 0000000000000000 [ 36.588589] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7540780 [ 36.595831] R13: ffff8801cb518008 R14: 0000000000000000 R15: ffffffff83013be0 [ 36.603088] FS: 0000000000905880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 36.611286] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.617139] CR2: 0000000000000080 CR3: 00000001da3c0000 CR4: 00000000001606f0 [ 36.624382] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 36.631633] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 36.638872] Stack: [ 36.640995] ffff8801c94b1980 ffff8801cb518000 ffff8801c94b1d50 ffff8801c94b1c58 [ 36.648980] ffff8801d9be7ce8 ffffffff836c45f2 ffff8801c94b1dc0 ffff8801c94b1980 [ 36.656960] ffffffff836c4520 ffff8801d9be7d20 ffffffff83021095 ffff8801c94b1dc0 [ 36.664949] Call Trace: [ 36.667511] [] pppol2tp_session_destruct+0xd2/0x110 [ 36.674144] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 36.680432] [] __sk_destruct+0x55/0x590 [ 36.686026] [] ? sock_release+0x1c0/0x1c0 [ 36.691793] [] sk_destruct+0x63/0x80 [ 36.697126] [] __sk_free+0x4f/0x220 [ 36.702373] [] sk_free+0x2b/0x40 [ 36.707360] [] pppol2tp_release+0x239/0x2e0 [ 36.713303] [] sock_release+0x96/0x1c0 [ 36.718810] [] sock_close+0x16/0x20 [ 36.724072] [] __fput+0x263/0x700 [ 36.729144] [] ____fput+0x15/0x20 [ 36.734221] [] task_work_run+0x10c/0x180 [ 36.739903] [] exit_to_usermode_loop+0xfc/0x120 [ 36.746193] [] do_syscall_64+0x364/0x490 [ 36.751874] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 36.758770] 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 [ 36.785723] RIP [] l2tp_session_free+0x11c/0x200 [ 36.792242] RSP [ 36.795838] CR2: 0000000000000080 [ 36.800713] ---[ end trace b9085ef4adb667a8 ]--- [ 36.805489] Kernel panic - not syncing: Fatal exception [ 36.811231] Dumping ftrace buffer: [ 36.814741] (ftrace buffer empty) [ 36.818424] Kernel Offset: disabled [ 36.822023] Rebooting in 86400 seconds..