[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 11.863815] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.953576] random: sshd: uninitialized urandom read (32 bytes read) [ 18.106742] random: sshd: uninitialized urandom read (32 bytes read) [ 18.606426] random: sshd: uninitialized urandom read (32 bytes read) [ 35.194303] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.40' (ECDSA) to the list of known hosts. [ 40.987366] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 41.208930] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 41.217391] IP: [] l2tp_session_free+0x11c/0x200 [ 41.224156] PGD 1bcd31067 [ 41.227104] PUD 1bce50067 PMD 0 [ 41.230738] [ 41.232383] Oops: 0002 [#1] PREEMPT SMP KASAN [ 41.236954] Dumping ftrace buffer: [ 41.240582] (ftrace buffer empty) [ 41.244286] Modules linked in: [ 41.247595] CPU: 0 PID: 3797 Comm: syz-executor276 Not tainted 4.9.122-g54068d6 #78 [ 41.255512] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.264856] task: ffff8801b9c34800 task.stack: ffff8801b89f0000 [ 41.271205] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 41.280099] RSP: 0018:ffff8801b89f7ca0 EFLAGS: 00010246 [ 41.285657] RAX: dffffc0000000000 RBX: ffff8801c8396a00 RCX: 0000000000000000 [ 41.293017] RDX: 1ffff10037195520 RSI: ffffffff836c39a1 RDI: ffff8801b8caa900 [ 41.300409] RBP: ffff8801b89f7cc0 R08: ffff8801b9c350e8 R09: 0000000000000000 [ 41.307936] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b8caa780 [ 41.315196] R13: ffff8801c8396a08 R14: 0000000000000000 R15: ffffffff83019be0 [ 41.322455] FS: 0000000000d53880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 41.330690] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.336563] CR2: 0000000000000080 CR3: 00000001bb9e2000 CR4: 00000000001606f0 [ 41.343831] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 41.351088] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 41.358345] Stack: [ 41.360502] ffff8801d94a1980 ffff8801c8396a00 ffff8801d94a1d50 ffff8801d94a1c58 [ 41.368559] ffff8801b89f7ce8 ffffffff836cb2b2 ffff8801d94a1dc0 ffff8801d94a1980 [ 41.376646] ffffffff836cb1e0 ffff8801b89f7d20 ffffffff830270f5 ffff8801d94a1dc0 [ 41.384702] Call Trace: [ 41.387289] [] pppol2tp_session_destruct+0xd2/0x110 [ 41.393943] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 41.400250] [] __sk_destruct+0x55/0x590 [ 41.405862] [] ? sock_release+0x1c0/0x1c0 [ 41.411761] [] sk_destruct+0x63/0x80 [ 41.417118] [] __sk_free+0x4f/0x220 [ 41.422386] [] sk_free+0x2b/0x40 [ 41.427397] [] pppol2tp_release+0x239/0x2e0 [ 41.433510] [] sock_release+0x96/0x1c0 [ 41.439049] [] sock_close+0x16/0x20 [ 41.444449] [] __fput+0x263/0x700 [ 41.449543] [] ____fput+0x15/0x20 [ 41.454636] [] task_work_run+0x10c/0x180 [ 41.460336] [] exit_to_usermode_loop+0xfc/0x120 [ 41.466653] [] do_syscall_64+0x364/0x490 [ 41.472363] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 41.479281] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 41.507200] RIP [] l2tp_session_free+0x11c/0x200 [ 41.513732] RSP [ 41.517346] CR2: 0000000000000080 [ 41.522447] ---[ end trace 83db178126caf1d9 ]--- [ 41.527232] Kernel panic - not syncing: Fatal exception [ 41.532897] Dumping ftrace buffer: [ 41.536434] (ftrace buffer empty) [ 41.540132] Kernel Offset: disabled [ 41.543749] Rebooting in 86400 seconds..