[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.139892] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.984395] random: sshd: uninitialized urandom read (32 bytes read) [ 21.316211] random: sshd: uninitialized urandom read (32 bytes read) [ 21.851519] random: sshd: uninitialized urandom read (32 bytes read) [ 25.316552] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.15' (ECDSA) to the list of known hosts. [ 31.043756] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 31.263181] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 31.271562] IP: [] l2tp_session_free+0x11c/0x200 [ 31.277988] PGD 1c96bf067 [ 31.280631] PUD 1cb7e6067 PMD 0 [ 31.284114] [ 31.285779] Oops: 0002 [#1] PREEMPT SMP KASAN [ 31.290266] Dumping ftrace buffer: [ 31.293781] (ftrace buffer empty) [ 31.297467] Modules linked in: [ 31.300756] CPU: 1 PID: 3803 Comm: syz-executor036 Not tainted 4.9.123-g8dd3fc2 #79 [ 31.308520] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.317850] task: ffff8801b7ab1800 task.stack: ffff8801b6500000 [ 31.323882] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 31.332731] RSP: 0018:ffff8801b6507ca0 EFLAGS: 00010246 [ 31.338152] RAX: dffffc0000000000 RBX: ffff8801b6bea280 RCX: 0000000000000000 [ 31.345395] RDX: 1ffff10036d301c0 RSI: ffffffff836c4991 RDI: ffff8801b6980e00 [ 31.352639] RBP: ffff8801b6507cc0 R08: ffff8801b7ab20e8 R09: 0000000000000000 [ 31.359886] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6980c80 [ 31.367137] R13: ffff8801b6bea288 R14: 0000000000000000 R15: ffffffff8301abe0 [ 31.374387] FS: 0000000000cb9880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 31.382597] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.388456] CR2: 0000000000000080 CR3: 00000001c9190000 CR4: 00000000001606f0 [ 31.395710] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 31.402967] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 31.410214] Stack: [ 31.412336] ffff8801cb794400 ffff8801b6bea280 ffff8801cb7947d0 ffff8801cb7946d8 [ 31.420331] ffff8801b6507ce8 ffffffff836cc2a2 ffff8801cb794840 ffff8801cb794400 [ 31.428339] ffffffff836cc1d0 ffff8801b6507d20 ffffffff830280f5 ffff8801cb794840 [ 31.436352] Call Trace: [ 31.438925] [] pppol2tp_session_destruct+0xd2/0x110 [ 31.445566] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.451913] [] __sk_destruct+0x55/0x590 [ 31.457528] [] ? sock_release+0x1c0/0x1c0 [ 31.463303] [] sk_destruct+0x63/0x80 [ 31.468640] [] __sk_free+0x4f/0x220 [ 31.473891] [] sk_free+0x2b/0x40 [ 31.478880] [] pppol2tp_release+0x239/0x2e0 [ 31.484825] [] sock_release+0x96/0x1c0 [ 31.490334] [] sock_close+0x16/0x20 [ 31.495590] [] __fput+0x263/0x700 [ 31.500674] [] ____fput+0x15/0x20 [ 31.505751] [] task_work_run+0x10c/0x180 [ 31.511436] [] exit_to_usermode_loop+0xfc/0x120 [ 31.517732] [] do_syscall_64+0x364/0x490 [ 31.523417] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.530312] 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 e5 c3 c9 fd 4c 89 ea 48 b8 00 [ 31.557159] RIP [] l2tp_session_free+0x11c/0x200 [ 31.563672] RSP [ 31.567267] CR2: 0000000000000080 [ 31.570821] ---[ end trace e1993bbb7f918b69 ]--- [ 31.575598] Kernel panic - not syncing: Fatal exception [ 31.581267] Dumping ftrace buffer: [ 31.584786] (ftrace buffer empty) [ 31.588469] Kernel Offset: disabled [ 31.592067] Rebooting in 86400 seconds..