[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.771116] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.560178] random: sshd: uninitialized urandom read (32 bytes read) [ 28.740713] random: sshd: uninitialized urandom read (32 bytes read) [ 29.235254] random: sshd: uninitialized urandom read (32 bytes read) [ 59.751794] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.33' (ECDSA) to the list of known hosts. [ 67.206806] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 67.414096] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 67.422327] IP: [] l2tp_session_free+0x11c/0x200 [ 67.428754] PGD 1c63b3067 [ 67.431400] PUD 1c63a9067 PMD 0 [ 67.434882] [ 67.436508] Oops: 0002 [#1] PREEMPT SMP KASAN [ 67.440980] Dumping ftrace buffer: [ 67.444588] (ftrace buffer empty) [ 67.448274] Modules linked in: [ 67.451564] CPU: 1 PID: 3830 Comm: syz-executor242 Not tainted 4.9.121-g681e57b #25 [ 67.459331] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 67.468668] task: ffff8801c719c800 task.stack: ffff8801b5190000 [ 67.474702] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 67.483587] RSP: 0018:ffff8801b5197ca0 EFLAGS: 00010246 [ 67.489056] RAX: dffffc0000000000 RBX: ffff8801c5015680 RCX: 0000000000000000 [ 67.496347] RDX: 1ffff10038a384d0 RSI: ffffffff836c29a1 RDI: ffff8801c51c2680 [ 67.503609] RBP: ffff8801b5197cc0 R08: ffff8801c719d0e8 R09: 0000000000000000 [ 67.510904] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c51c2500 [ 67.518165] R13: ffff8801c5015688 R14: 0000000000000000 R15: ffffffff83018be0 [ 67.525503] FS: 0000000000e9e880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 67.533708] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 67.541543] CR2: 0000000000000080 CR3: 00000001c86d2000 CR4: 00000000001606f0 [ 67.548804] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 67.556065] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 67.563312] Stack: [ 67.565442] ffff8801b51ba200 ffff8801c5015680 ffff8801b51ba5d0 ffff8801b51ba4d8 [ 67.573449] ffff8801b5197ce8 ffffffff836ca2b2 ffff8801b51ba640 ffff8801b51ba200 [ 67.582070] ffffffff836ca1e0 ffff8801b5197d20 ffffffff830260f5 ffff8801b51ba640 [ 67.590151] Call Trace: [ 67.592772] [] pppol2tp_session_destruct+0xd2/0x110 [ 67.599424] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 67.605728] [] __sk_destruct+0x55/0x590 [ 67.611331] [] ? sock_release+0x1c0/0x1c0 [ 67.617106] [] sk_destruct+0x63/0x80 [ 67.622452] [] __sk_free+0x4f/0x220 [ 67.627710] [] sk_free+0x2b/0x40 [ 67.632709] [] pppol2tp_release+0x239/0x2e0 [ 67.638661] [] sock_release+0x96/0x1c0 [ 67.644236] [] sock_close+0x16/0x20 [ 67.649508] [] __fput+0x263/0x700 [ 67.654609] [] ____fput+0x15/0x20 [ 67.659700] [] task_work_run+0x10c/0x180 [ 67.665391] [] exit_to_usermode_loop+0xfc/0x120 [ 67.671785] [] do_syscall_64+0x364/0x490 [ 67.677496] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 67.684409] 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 65 df c9 fd 4c 89 ea 48 b8 00 [ 67.711549] RIP [] l2tp_session_free+0x11c/0x200 [ 67.718073] RSP [ 67.721673] CR2: 0000000000000080 [ 67.725198] ---[ end trace 300a2d52f5d3a4df ]--- [ 67.729953] Kernel panic - not syncing: Fatal exception [ 67.735636] Dumping ftrace buffer: [ 67.739227] (ftrace buffer empty) [ 67.742921] Kernel Offset: disabled [ 67.746562] Rebooting in 86400 seconds..