[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.982580] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.478215] random: sshd: uninitialized urandom read (32 bytes read) [ 22.840069] random: sshd: uninitialized urandom read (32 bytes read) [ 23.398025] random: sshd: uninitialized urandom read (32 bytes read) [ 23.552742] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.58' (ECDSA) to the list of known hosts. [ 28.984835] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.186201] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.194441] IP: [] l2tp_session_free+0x11c/0x200 [ 29.200877] PGD 1c06b3067 [ 29.203518] PUD 1c067b067 PMD 0 [ 29.206997] [ 29.208624] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.213094] Dumping ftrace buffer: [ 29.216607] (ftrace buffer empty) [ 29.220289] Modules linked in: [ 29.223573] CPU: 0 PID: 3800 Comm: syz-executor028 Not tainted 4.9.118-g47b77b8 #72 [ 29.231337] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.240770] task: ffff8801b7900000 task.stack: ffff8801d9088000 [ 29.246801] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 29.255660] RSP: 0018:ffff8801d908fca0 EFLAGS: 00010246 [ 29.261082] RAX: dffffc0000000000 RBX: ffff8801c90a8000 RCX: 0000000000000000 [ 29.268451] RDX: 1ffff10036c24cd0 RSI: ffffffff836bf781 RDI: ffff8801b6126680 [ 29.275697] RBP: ffff8801d908fcc0 R08: ffff8801b79008e8 R09: 0000000000000000 [ 29.282944] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6126500 [ 29.290190] R13: ffff8801c90a8008 R14: 0000000000000000 R15: ffffffff83015be0 [ 29.297437] FS: 0000000001d18880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 29.305637] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.311492] CR2: 0000000000000080 CR3: 00000001c92ce000 CR4: 00000000001606f0 [ 29.318741] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 29.325989] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 29.333234] Stack: [ 29.335358] ffff8801ca100880 ffff8801c90a8000 ffff8801ca100c50 ffff8801ca100b58 [ 29.343355] ffff8801d908fce8 ffffffff836c7092 ffff8801ca100cc0 ffff8801ca100880 [ 29.351359] ffffffff836c6fc0 ffff8801d908fd20 ffffffff830230f5 ffff8801ca100cc0 [ 29.359396] Call Trace: [ 29.361964] [] pppol2tp_session_destruct+0xd2/0x110 [ 29.368606] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 29.374903] [] __sk_destruct+0x55/0x590 [ 29.380507] [] ? sock_release+0x1c0/0x1c0 [ 29.386278] [] sk_destruct+0x63/0x80 [ 29.391616] [] __sk_free+0x4f/0x220 [ 29.396872] [] sk_free+0x2b/0x40 [ 29.401870] [] pppol2tp_release+0x239/0x2e0 [ 29.407816] [] sock_release+0x96/0x1c0 [ 29.413388] [] sock_close+0x16/0x20 [ 29.418653] [] __fput+0x263/0x700 [ 29.423729] [] ____fput+0x15/0x20 [ 29.428806] [] task_work_run+0x10c/0x180 [ 29.434490] [] exit_to_usermode_loop+0xfc/0x120 [ 29.440777] [] do_syscall_64+0x364/0x490 [ 29.446461] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.453355] 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 f5 f2 c9 fd 4c 89 ea 48 b8 00 [ 29.480119] RIP [] l2tp_session_free+0x11c/0x200 [ 29.486620] RSP [ 29.490219] CR2: 0000000000000080 [ 29.494084] ---[ end trace 6715c6edafa0803d ]--- [ 29.498893] Kernel panic - not syncing: Fatal exception [ 29.504566] Dumping ftrace buffer: [ 29.508083] (ftrace buffer empty) [ 29.511764] Kernel Offset: disabled [ 29.515360] Rebooting in 86400 seconds..