[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.730770] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.420539] random: sshd: uninitialized urandom read (32 bytes read) [ 27.936876] random: sshd: uninitialized urandom read (32 bytes read) [ 28.594498] random: sshd: uninitialized urandom read (32 bytes read) [ 28.730288] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.51' (ECDSA) to the list of known hosts. [ 34.128080] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.346609] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.354843] IP: [] l2tp_session_free+0x11c/0x200 [ 34.361262] PGD 1c24e0067 [ 34.363924] PUD 1c96f8067 PMD 0 [ 34.367404] [ 34.369034] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.373510] Dumping ftrace buffer: [ 34.377045] (ftrace buffer empty) [ 34.380735] Modules linked in: [ 34.384047] CPU: 1 PID: 3807 Comm: syz-executor383 Not tainted 4.9.113-g47bbcd6 #62 [ 34.391820] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.401151] task: ffff8801b8f06000 task.stack: ffff8801b7370000 [ 34.407180] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.416035] RSP: 0018:ffff8801b7377ca0 EFLAGS: 00010246 [ 34.421467] RAX: dffffc0000000000 RBX: ffff8801b74ca780 RCX: 0000000000000000 [ 34.428726] RDX: 1ffff100396f2eb0 RSI: ffffffff836bcce1 RDI: ffff8801cb797580 [ 34.435981] RBP: ffff8801b7377cc0 R08: ffff8801b8f068e8 R09: 0000000000000000 [ 34.443235] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb797400 [ 34.450485] R13: ffff8801b74ca788 R14: 0000000000000000 R15: ffffffff83013be0 [ 34.457750] FS: 0000000001e83880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 34.465971] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.471839] CR2: 0000000000000080 CR3: 00000001bfc98000 CR4: 00000000001606f0 [ 34.479088] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.486342] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.493592] Stack: [ 34.495731] ffff8801b8372200 ffff8801b74ca780 ffff8801b83725d0 ffff8801b83724d8 [ 34.503820] ffff8801b7377ce8 ffffffff836c45f2 ffff8801b8372640 ffff8801b8372200 [ 34.511828] ffffffff836c4520 ffff8801b7377d20 ffffffff83021095 ffff8801b8372640 [ 34.519846] Call Trace: [ 34.522426] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.529082] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.535381] [] __sk_destruct+0x55/0x590 [ 34.540996] [] ? sock_release+0x1c0/0x1c0 [ 34.546773] [] sk_destruct+0x63/0x80 [ 34.552119] [] __sk_free+0x4f/0x220 [ 34.557370] [] sk_free+0x2b/0x40 [ 34.562361] [] pppol2tp_release+0x239/0x2e0 [ 34.568307] [] sock_release+0x96/0x1c0 [ 34.573829] [] sock_close+0x16/0x20 [ 34.579080] [] __fput+0x263/0x700 [ 34.584157] [] ____fput+0x15/0x20 [ 34.589237] [] task_work_run+0x10c/0x180 [ 34.594933] [] exit_to_usermode_loop+0xfc/0x120 [ 34.601224] [] do_syscall_64+0x364/0x490 [ 34.606909] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.613802] 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 [ 34.640754] RIP [] l2tp_session_free+0x11c/0x200 [ 34.647262] RSP [ 34.650881] CR2: 0000000000000080 [ 34.654385] ---[ end trace b597af70f7a58e76 ]--- [ 34.659144] Kernel panic - not syncing: Fatal exception [ 34.664968] Dumping ftrace buffer: [ 34.668488] (ftrace buffer empty) [ 34.672172] Kernel Offset: disabled [ 34.675770] Rebooting in 86400 seconds..