[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.107241] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.380534] random: sshd: uninitialized urandom read (32 bytes read) [ 17.689224] random: sshd: uninitialized urandom read (32 bytes read) [ 18.742647] random: sshd: uninitialized urandom read (32 bytes read) [ 20.224882] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.4' (ECDSA) to the list of known hosts. [ 25.635007] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.891000] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.899231] IP: [] l2tp_session_free+0x11c/0x200 [ 25.905678] PGD 1bfe2a067 [ 25.908320] PUD 1bfe2b067 PMD 0 [ 25.911793] [ 25.913413] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.917898] Dumping ftrace buffer: [ 25.921410] (ftrace buffer empty) [ 25.925093] Modules linked in: [ 25.928379] CPU: 1 PID: 3777 Comm: syz-executor045 Not tainted 4.9.116-g0137ea2 #18 [ 25.936143] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.945472] task: ffff8801ba698000 task.stack: ffff8801ba340000 [ 25.951507] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.960382] RSP: 0018:ffff8801ba347ca0 EFLAGS: 00010246 [ 25.965810] RAX: dffffc0000000000 RBX: ffff8801ba47c500 RCX: 0000000000000000 [ 25.973061] RDX: 1ffff100396e2a10 RSI: ffffffff836be8f1 RDI: ffff8801cb715080 [ 25.980306] RBP: ffff8801ba347cc0 R08: ffff8801ba6988e8 R09: 0000000000000000 [ 25.987563] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb714f00 [ 25.994907] R13: ffff8801ba47c508 R14: 0000000000000000 R15: ffffffff83014be0 [ 26.002155] FS: 0000000000845880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.010450] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.016305] CR2: 0000000000000080 CR3: 00000001c39b2000 CR4: 00000000001606f0 [ 26.023551] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.030795] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.038072] Stack: [ 26.040207] ffff8801d95e3300 ffff8801ba47c500 ffff8801d95e36d0 ffff8801d95e35d8 [ 26.048212] ffff8801ba347ce8 ffffffff836c6202 ffff8801d95e3740 ffff8801d95e3300 [ 26.056216] ffffffff836c6130 ffff8801ba347d20 ffffffff83022095 ffff8801d95e3740 [ 26.064203] Call Trace: [ 26.066774] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.073414] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.079711] [] __sk_destruct+0x55/0x590 [ 26.085328] [] ? sock_release+0x1c0/0x1c0 [ 26.091100] [] sk_destruct+0x63/0x80 [ 26.096438] [] __sk_free+0x4f/0x220 [ 26.101705] [] sk_free+0x2b/0x40 [ 26.106696] [] pppol2tp_release+0x239/0x2e0 [ 26.112645] [] sock_release+0x96/0x1c0 [ 26.118157] [] sock_close+0x16/0x20 [ 26.123424] [] __fput+0x263/0x700 [ 26.128503] [] ____fput+0x15/0x20 [ 26.133585] [] task_work_run+0x10c/0x180 [ 26.139286] [] exit_to_usermode_loop+0xfc/0x120 [ 26.145579] [] do_syscall_64+0x364/0x490 [ 26.151268] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.158180] 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 01 ca fd 4c 89 ea 48 b8 00 [ 26.185162] RIP [] l2tp_session_free+0x11c/0x200 [ 26.191667] RSP [ 26.195280] CR2: 0000000000000080 [ 26.198822] ---[ end trace 3979ac85e527b7d1 ]--- [ 26.203588] Kernel panic - not syncing: Fatal exception [ 26.209311] Dumping ftrace buffer: [ 26.212836] (ftrace buffer empty) [ 26.216520] Kernel Offset: disabled [ 26.220120] Rebooting in 86400 seconds..