[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.488712] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.766308] random: sshd: uninitialized urandom read (32 bytes read) [ 15.112093] random: sshd: uninitialized urandom read (32 bytes read) [ 16.058280] random: sshd: uninitialized urandom read (32 bytes read) [ 16.199176] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.29' (ECDSA) to the list of known hosts. [ 21.568472] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.769587] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.777856] IP: [] l2tp_session_free+0x11c/0x200 [ 21.784296] PGD 1be7c3067 [ 21.786976] PUD 1be599067 PMD 0 [ 21.790516] [ 21.792167] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.796643] Dumping ftrace buffer: [ 21.800175] (ftrace buffer empty) [ 21.803872] Modules linked in: [ 21.807179] CPU: 1 PID: 3789 Comm: syz-executor787 Not tainted 4.9.113-g47bbcd6 #62 [ 21.814957] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.824331] task: ffff8801b9f21800 task.stack: ffff8801d8fa0000 [ 21.830386] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.839243] RSP: 0018:ffff8801d8fa7ca0 EFLAGS: 00010246 [ 21.844668] RAX: dffffc0000000000 RBX: ffff8801b72b6000 RCX: 0000000000000000 [ 21.851928] RDX: 1ffff1003b2c78d0 RSI: ffffffff836bcce1 RDI: ffff8801d963c680 [ 21.859620] RBP: ffff8801d8fa7cc0 R08: ffff8801b9f220e8 R09: 0000000000000000 [ 21.867219] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d963c500 [ 21.874475] R13: ffff8801b72b6008 R14: 0000000000000000 R15: ffffffff83013be0 [ 21.881762] FS: 0000000000fcb880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.889994] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.895875] CR2: 0000000000000080 CR3: 00000001bf74b000 CR4: 00000000001606f0 [ 21.903135] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.910386] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.917639] Stack: [ 21.919790] ffff8801b74faa80 ffff8801b72b6000 ffff8801b74fae50 ffff8801b74fad58 [ 21.927839] ffff8801d8fa7ce8 ffffffff836c45f2 ffff8801b74faec0 ffff8801b74faa80 [ 21.935856] ffffffff836c4520 ffff8801d8fa7d20 ffffffff83021095 ffff8801b74faec0 [ 21.943890] Call Trace: [ 21.946466] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.953123] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.959429] [] __sk_destruct+0x55/0x590 [ 21.965057] [] ? sock_release+0x1c0/0x1c0 [ 21.970848] [] sk_destruct+0x63/0x80 [ 21.976219] [] __sk_free+0x4f/0x220 [ 21.981488] [] sk_free+0x2b/0x40 [ 21.986521] [] pppol2tp_release+0x239/0x2e0 [ 21.992498] [] sock_release+0x96/0x1c0 [ 21.998049] [] sock_close+0x16/0x20 [ 22.003322] [] __fput+0x263/0x700 [ 22.008411] [] ____fput+0x15/0x20 [ 22.013511] [] task_work_run+0x10c/0x180 [ 22.019213] [] exit_to_usermode_loop+0xfc/0x120 [ 22.025522] [] do_syscall_64+0x364/0x490 [ 22.031236] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.038137] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 22.065652] RIP [] l2tp_session_free+0x11c/0x200 [ 22.072198] RSP [ 22.075895] CR2: 0000000000000080 [ 22.079479] ---[ end trace c1a28a91b07956db ]--- [ 22.084234] Kernel panic - not syncing: Fatal exception [ 22.092703] Dumping ftrace buffer: [ 22.096242] (ftrace buffer empty) [ 22.099937] Kernel Offset: disabled [ 22.103545] Rebooting in 86400 seconds..