[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.568459] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.591837] random: sshd: uninitialized urandom read (32 bytes read) [ 28.165557] random: sshd: uninitialized urandom read (32 bytes read) [ 28.665551] random: sshd: uninitialized urandom read (32 bytes read) [ 28.802977] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.11' (ECDSA) to the list of known hosts. [ 34.393611] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.628119] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.636609] IP: [] l2tp_session_free+0x11c/0x200 [ 34.643125] PGD 1b8709067 [ 34.645785] PUD 1b7a27067 PMD 0 [ 34.649273] [ 34.650900] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.655381] Dumping ftrace buffer: [ 34.658902] (ftrace buffer empty) [ 34.662596] Modules linked in: [ 34.665904] CPU: 0 PID: 3805 Comm: syz-executor159 Not tainted 4.9.119-g92e8704 #74 [ 34.673798] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.683274] task: ffff8801b6cb0000 task.stack: ffff8801d9790000 [ 34.689470] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.698459] RSP: 0018:ffff8801d9797ca0 EFLAGS: 00010246 [ 34.703890] RAX: dffffc0000000000 RBX: ffff8801b5818280 RCX: 0000000000000000 [ 34.711254] RDX: 1ffff10036af1920 RSI: ffffffff836bf9a1 RDI: ffff8801b578c900 [ 34.718523] RBP: ffff8801d9797cc0 R08: ffff8801b6cb08e8 R09: 0000000000000000 [ 34.725804] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b578c780 [ 34.725807] R13: ffff8801b5818288 R14: 0000000000000000 R15: ffffffff83015be0 [ 34.725811] FS: 0000000001e5c880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.725814] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.725823] CR2: 0000000000000080 CR3: 00000001b6d14000 CR4: 00000000001606f0 [ 34.725828] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.725830] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.725831] Stack: [ 34.725841] ffff8801b565b300 ffff8801b5818280 ffff8801b565b6d0 ffff8801b565b5d8 [ 34.725846] ffff8801d9797ce8 ffffffff836c72b2 ffff8801b565b740 ffff8801b565b300 [ 34.725852] ffffffff836c71e0 ffff8801d9797d20 ffffffff830230f5 ffff8801b565b740 [ 34.725853] Call Trace: [ 34.725866] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.725870] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.725875] [] __sk_destruct+0x55/0x590 [ 34.725881] [] ? sock_release+0x1c0/0x1c0 [ 34.725884] [] sk_destruct+0x63/0x80 [ 34.725888] [] __sk_free+0x4f/0x220 [ 34.725894] [] sk_free+0x2b/0x40 [ 34.725898] [] pppol2tp_release+0x239/0x2e0 [ 34.725902] [] sock_release+0x96/0x1c0 [ 34.725906] [] sock_close+0x16/0x20 [ 34.725911] [] __fput+0x263/0x700 [ 34.725916] [] ____fput+0x15/0x20 [ 34.725922] [] task_work_run+0x10c/0x180 [ 34.725928] [] exit_to_usermode_loop+0xfc/0x120 [ 34.725931] [] do_syscall_64+0x364/0x490 [ 34.725937] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.726022] 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 f0 c9 fd 4c 89 ea 48 b8 00 [ 34.726027] RIP [] l2tp_session_free+0x11c/0x200 [ 34.726028] RSP [ 34.726030] CR2: 0000000000000080 [ 34.728338] ---[ end trace 317ac78f985e1c14 ]--- [ 34.728341] Kernel panic - not syncing: Fatal exception [ 34.733591] Dumping ftrace buffer: [ 34.733594] (ftrace buffer empty) [ 34.733596] Kernel Offset: disabled [ 34.950028] Rebooting in 86400 seconds..