[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.011310] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.624007] random: sshd: uninitialized urandom read (32 bytes read) [ 19.169572] random: sshd: uninitialized urandom read (32 bytes read) [ 19.651782] random: sshd: uninitialized urandom read (32 bytes read) [ 19.790493] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.4' (ECDSA) to the list of known hosts. [ 25.210960] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.432892] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.441110] IP: [] l2tp_session_free+0x11c/0x200 [ 25.447545] PGD 1c4fc5067 [ 25.450188] PUD 1cb491067 PMD 0 [ 25.453670] [ 25.455300] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.459771] Dumping ftrace buffer: [ 25.463357] (ftrace buffer empty) [ 25.467049] Modules linked in: [ 25.470352] CPU: 0 PID: 3801 Comm: syz-executor984 Not tainted 4.9.119-g92e8704 #22 [ 25.478201] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.487538] task: ffff8801b7066000 task.stack: ffff8801b5868000 [ 25.493646] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.502601] RSP: 0018:ffff8801b586fca0 EFLAGS: 00010246 [ 25.508024] RAX: dffffc0000000000 RBX: ffff8801b744db80 RCX: 0000000000000000 [ 25.515337] RDX: 1ffff10036b72ab0 RSI: ffffffff836bf9a1 RDI: ffff8801b5b95580 [ 25.522587] RBP: ffff8801b586fcc0 R08: ffff8801b70668e8 R09: 0000000000000000 [ 25.529836] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5b95400 [ 25.537080] R13: ffff8801b744db88 R14: 0000000000000000 R15: ffffffff83015be0 [ 25.544422] FS: 0000000001f8c880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.552627] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.558482] CR2: 0000000000000080 CR3: 00000001ca7ec000 CR4: 00000000001606f0 [ 25.565737] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.572983] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.580230] Stack: [ 25.582358] ffff8801b5bc9980 ffff8801b744db80 ffff8801b5bc9d50 ffff8801b5bc9c58 [ 25.590423] ffff8801b586fce8 ffffffff836c72b2 ffff8801b5bc9dc0 ffff8801b5bc9980 [ 25.598472] ffffffff836c71e0 ffff8801b586fd20 ffffffff830230f5 ffff8801b5bc9dc0 [ 25.606472] Call Trace: [ 25.609045] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.615693] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.622052] [] __sk_destruct+0x55/0x590 [ 25.627659] [] ? sock_release+0x1c0/0x1c0 [ 25.633434] [] sk_destruct+0x63/0x80 [ 25.638774] [] __sk_free+0x4f/0x220 [ 25.644025] [] sk_free+0x2b/0x40 [ 25.649025] [] pppol2tp_release+0x239/0x2e0 [ 25.654981] [] sock_release+0x96/0x1c0 [ 25.660572] [] sock_close+0x16/0x20 [ 25.665834] [] __fput+0x263/0x700 [ 25.670913] [] ____fput+0x15/0x20 [ 25.676000] [] task_work_run+0x10c/0x180 [ 25.681688] [] exit_to_usermode_loop+0xfc/0x120 [ 25.687990] [] do_syscall_64+0x364/0x490 [ 25.693680] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.700626] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 25.727795] RIP [] l2tp_session_free+0x11c/0x200 [ 25.734302] RSP [ 25.737901] CR2: 0000000000000080 [ 25.741421] ---[ end trace 42ce644692d5e68d ]--- [ 25.746188] Kernel panic - not syncing: Fatal exception [ 25.752029] Dumping ftrace buffer: [ 25.755546] (ftrace buffer empty) [ 25.759339] Kernel Offset: disabled [ 25.762938] Rebooting in 86400 seconds..