[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.727928] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.209324] random: sshd: uninitialized urandom read (32 bytes read) [ 23.597039] random: sshd: uninitialized urandom read (32 bytes read) [ 24.349419] random: sshd: uninitialized urandom read (32 bytes read) [ 24.480137] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.29' (ECDSA) to the list of known hosts. [ 29.906982] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.115508] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.123752] IP: [] l2tp_session_free+0x11c/0x200 [ 30.130183] PGD 1b66a0067 [ 30.132828] PUD 1b654a067 PMD 0 [ 30.136328] [ 30.137960] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.142438] Dumping ftrace buffer: [ 30.145956] (ftrace buffer empty) [ 30.149643] Modules linked in: [ 30.153040] CPU: 0 PID: 3806 Comm: syz-executor511 Not tainted 4.9.113-g47bbcd6 #10 [ 30.160825] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.170173] task: ffff8801b64e0000 task.stack: ffff8801b5378000 [ 30.176213] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.185086] RSP: 0018:ffff8801b537fca0 EFLAGS: 00010246 [ 30.190532] RAX: dffffc0000000000 RBX: ffff8801cb122a00 RCX: 0000000000000000 [ 30.197787] RDX: 1ffff10036a4c8d0 RSI: ffffffff836bcce1 RDI: ffff8801b5264680 [ 30.205036] RBP: ffff8801b537fcc0 R08: ffff8801b64e08e8 R09: 0000000000000000 [ 30.212286] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5264500 [ 30.219550] R13: ffff8801cb122a08 R14: 0000000000000000 R15: ffffffff83013be0 [ 30.226817] FS: 0000000000e5c880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 30.235020] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.240883] CR2: 0000000000000080 CR3: 00000001c95c8000 CR4: 00000000001606f0 [ 30.248137] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.255407] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.262652] Stack: [ 30.264795] ffff8801cb3b6600 ffff8801cb122a00 ffff8801cb3b69d0 ffff8801cb3b68d8 [ 30.272799] ffff8801b537fce8 ffffffff836c45f2 ffff8801cb3b6a40 ffff8801cb3b6600 [ 30.280808] ffffffff836c4520 ffff8801b537fd20 ffffffff83021095 ffff8801cb3b6a40 [ 30.288836] Call Trace: [ 30.291412] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.298063] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.304362] [] __sk_destruct+0x55/0x590 [ 30.309962] [] ? sock_release+0x1c0/0x1c0 [ 30.315752] [] sk_destruct+0x63/0x80 [ 30.321105] [] __sk_free+0x4f/0x220 [ 30.326364] [] sk_free+0x2b/0x40 [ 30.331369] [] pppol2tp_release+0x239/0x2e0 [ 30.337328] [] sock_release+0x96/0x1c0 [ 30.342856] [] sock_close+0x16/0x20 [ 30.348136] [] __fput+0x263/0x700 [ 30.353220] [] ____fput+0x15/0x20 [ 30.358308] [] task_work_run+0x10c/0x180 [ 30.363998] [] exit_to_usermode_loop+0xfc/0x120 [ 30.370305] [] do_syscall_64+0x364/0x490 [ 30.376000] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.382906] 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 [ 30.410047] RIP [] l2tp_session_free+0x11c/0x200 [ 30.416738] RSP [ 30.420340] CR2: 0000000000000080 [ 30.424377] ---[ end trace 8273fc1bd8e9eacf ]--- [ 30.429188] Kernel panic - not syncing: Fatal exception [ 30.435200] Dumping ftrace buffer: [ 30.438732] (ftrace buffer empty) [ 30.442415] Kernel Offset: disabled [ 30.446016] Rebooting in 86400 seconds..