[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.192449] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.388135] random: sshd: uninitialized urandom read (32 bytes read) [ 17.849796] random: sshd: uninitialized urandom read (32 bytes read) [ 18.781441] random: sshd: uninitialized urandom read (32 bytes read) [ 30.221404] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.14' (ECDSA) to the list of known hosts. [ 35.764002] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 35.969362] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 35.977657] IP: [] l2tp_session_free+0x11c/0x200 [ 35.984082] PGD 1c8139067 [ 35.986723] PUD 1c5669067 PMD 0 [ 35.990203] [ 35.991835] Oops: 0002 [#1] PREEMPT SMP KASAN [ 35.996320] Dumping ftrace buffer: [ 35.999841] (ftrace buffer empty) [ 36.003531] Modules linked in: [ 36.006922] CPU: 1 PID: 3814 Comm: syz-executor611 Not tainted 4.9.113-g90e7a90 #16 [ 36.014695] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.024025] task: ffff8801b6874800 task.stack: ffff8801d91f8000 [ 36.030266] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 36.039120] RSP: 0018:ffff8801d91ffca0 EFLAGS: 00010246 [ 36.044545] RAX: dffffc0000000000 RBX: ffff8801c96dd900 RCX: 0000000000000000 [ 36.051807] RDX: 1ffff100392c7d70 RSI: ffffffff836bdee1 RDI: ffff8801c963eb80 [ 36.059053] RBP: ffff8801d91ffcc0 R08: ffff8801b68750e8 R09: 0000000000000000 [ 36.066301] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c963ea00 [ 36.073556] R13: ffff8801c96dd908 R14: 0000000000000000 R15: ffffffff83014be0 [ 36.080811] FS: 0000000000fd7880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 36.089014] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.094879] CR2: 0000000000000080 CR3: 00000001cb168000 CR4: 00000000001606f0 [ 36.102127] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 36.109380] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 36.116623] Stack: [ 36.118746] ffff8801da3b9980 ffff8801c96dd900 ffff8801da3b9d50 ffff8801da3b9c58 [ 36.126754] ffff8801d91ffce8 ffffffff836c57f2 ffff8801da3b9dc0 ffff8801da3b9980 [ 36.134810] ffffffff836c5720 ffff8801d91ffd20 ffffffff83022095 ffff8801da3b9dc0 [ 36.142827] Call Trace: [ 36.145423] [] pppol2tp_session_destruct+0xd2/0x110 [ 36.152064] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 36.158356] [] __sk_destruct+0x55/0x590 [ 36.163970] [] ? sock_release+0x1c0/0x1c0 [ 36.169747] [] sk_destruct+0x63/0x80 [ 36.175081] [] __sk_free+0x4f/0x220 [ 36.180328] [] sk_free+0x2b/0x40 [ 36.185315] [] pppol2tp_release+0x239/0x2e0 [ 36.191257] [] sock_release+0x96/0x1c0 [ 36.196775] [] sock_close+0x16/0x20 [ 36.202023] [] __fput+0x263/0x700 [ 36.207098] [] ____fput+0x15/0x20 [ 36.212176] [] task_work_run+0x10c/0x180 [ 36.217859] [] exit_to_usermode_loop+0xfc/0x120 [ 36.224157] [] do_syscall_64+0x364/0x490 [ 36.229841] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 36.236745] 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 0b ca fd 4c 89 ea 48 b8 00 [ 36.263648] RIP [] l2tp_session_free+0x11c/0x200 [ 36.270146] RSP [ 36.273741] CR2: 0000000000000080 [ 36.277237] ---[ end trace 8b7220ac92e524d3 ]--- [ 36.281994] Kernel panic - not syncing: Fatal exception [ 36.287714] Dumping ftrace buffer: [ 36.291231] (ftrace buffer empty) [ 36.294928] Kernel Offset: disabled [ 36.298556] Rebooting in 86400 seconds..