[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.255517] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.117021] random: sshd: uninitialized urandom read (32 bytes read) [ 20.595378] random: sshd: uninitialized urandom read (32 bytes read) [ 21.118444] random: sshd: uninitialized urandom read (32 bytes read) [ 21.261054] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.42' (ECDSA) to the list of known hosts. [ 26.894192] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.082936] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.091168] IP: [] l2tp_session_free+0x11c/0x200 [ 27.097597] PGD 1cb051067 [ 27.100242] PUD 1cb0ed067 PMD 0 [ 27.103724] [ 27.105359] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.109840] Dumping ftrace buffer: [ 27.113364] (ftrace buffer empty) [ 27.117062] Modules linked in: [ 27.120358] CPU: 1 PID: 3803 Comm: syz-executor167 Not tainted 4.9.122-g54068d6 #78 [ 27.128123] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.137460] task: ffff8801b794e000 task.stack: ffff8801d9578000 [ 27.143545] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.152404] RSP: 0018:ffff8801d957fca0 EFLAGS: 00010246 [ 27.157831] RAX: dffffc0000000000 RBX: ffff8801b63a6f00 RCX: 0000000000000000 [ 27.165086] RDX: 1ffff100393dba10 RSI: ffffffff836c39a1 RDI: ffff8801c9edd080 [ 27.172333] RBP: ffff8801d957fcc0 R08: ffff8801b794e8e8 R09: 0000000000000000 [ 27.179588] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9edcf00 [ 27.186837] R13: ffff8801b63a6f08 R14: 0000000000000000 R15: ffffffff83019be0 [ 27.194089] FS: 00000000011fa880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.202292] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.208150] CR2: 0000000000000080 CR3: 00000001c9cfc000 CR4: 00000000001606f0 [ 27.215397] Stack: [ 27.217526] ffff8801b61f6600 ffff8801b63a6f00 ffff8801b61f69d0 ffff8801b61f68d8 [ 27.225588] ffff8801d957fce8 ffffffff836cb2b2 ffff8801b61f6a40 ffff8801b61f6600 [ 27.233629] ffffffff836cb1e0 ffff8801d957fd20 ffffffff830270f5 ffff8801b61f6a40 [ 27.241639] Call Trace: [ 27.244210] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.250855] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.257163] [] __sk_destruct+0x55/0x590 [ 27.262773] [] ? sock_release+0x1c0/0x1c0 [ 27.268558] [] sk_destruct+0x63/0x80 [ 27.273924] [] __sk_free+0x4f/0x220 [ 27.279181] [] sk_free+0x2b/0x40 [ 27.284175] [] pppol2tp_release+0x239/0x2e0 [ 27.290124] [] sock_release+0x96/0x1c0 [ 27.295639] [] sock_close+0x16/0x20 [ 27.300899] [] __fput+0x263/0x700 [ 27.305980] [] ____fput+0x15/0x20 [ 27.311062] [] task_work_run+0x10c/0x180 [ 27.316756] [] exit_to_usermode_loop+0xfc/0x120 [ 27.323055] [] do_syscall_64+0x364/0x490 [ 27.328749] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.335652] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 27.362812] RIP [] l2tp_session_free+0x11c/0x200 [ 27.369324] RSP [ 27.372925] CR2: 0000000000000080 [ 27.376624] ---[ end trace 4eb9d2fd0942bd48 ]--- [ 27.381369] Kernel panic - not syncing: Fatal exception [ 27.387035] Dumping ftrace buffer: [ 27.390623] (ftrace buffer empty) [ 27.394541] Kernel Offset: disabled [ 27.398145] Rebooting in 86400 seconds..