[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.824925] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.154498] random: sshd: uninitialized urandom read (32 bytes read) [ 14.530680] random: sshd: uninitialized urandom read (32 bytes read) [ 15.030423] random: sshd: uninitialized urandom read (32 bytes read) [ 15.169048] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.51' (ECDSA) to the list of known hosts. [ 20.635825] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.811757] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 20.820001] IP: [] l2tp_session_free+0x11c/0x200 [ 20.826446] PGD 1c9f80067 [ 20.829083] PUD 1c9f82067 PMD 0 [ 20.832550] [ 20.834166] Oops: 0002 [#1] PREEMPT SMP KASAN [ 20.838632] Dumping ftrace buffer: [ 20.842146] (ftrace buffer empty) [ 20.845839] Modules linked in: [ 20.849121] CPU: 1 PID: 3781 Comm: syz-executor876 Not tainted 4.9.116-g0137ea2 #18 [ 20.856881] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.866207] task: ffff8801ba409800 task.stack: ffff8801ca738000 [ 20.872236] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 20.881081] RSP: 0018:ffff8801ca73fca0 EFLAGS: 00010246 [ 20.886567] RAX: dffffc0000000000 RBX: ffff8801cac04500 RCX: 0000000000000000 [ 20.893806] RDX: 1ffff10039580a10 RSI: ffffffff836be8f1 RDI: ffff8801cac05080 [ 20.901046] RBP: ffff8801ca73fcc0 R08: ffff8801ba40a0e8 R09: 0000000000000000 [ 20.908528] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cac04f00 [ 20.915791] R13: ffff8801cac04508 R14: 0000000000000000 R15: ffffffff83014be0 [ 20.923037] FS: 00000000023e4880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 20.931232] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.937086] CR2: 0000000000000080 CR3: 00000001c9fbd000 CR4: 00000000001606f0 [ 20.944347] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 20.951589] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 20.958836] Stack: [ 20.960973] ffff8801ba19dd80 ffff8801cac04500 ffff8801ba19e150 ffff8801ba19e058 [ 20.968958] ffff8801ca73fce8 ffffffff836c6202 ffff8801ba19e1c0 ffff8801ba19dd80 [ 20.976980] ffffffff836c6130 ffff8801ca73fd20 ffffffff83022095 ffff8801ba19e1c0 [ 20.984972] Call Trace: [ 20.987531] [] pppol2tp_session_destruct+0xd2/0x110 [ 20.994169] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.000458] [] __sk_destruct+0x55/0x590 [ 21.006056] [] ? sock_release+0x1c0/0x1c0 [ 21.011827] [] sk_destruct+0x63/0x80 [ 21.017171] [] __sk_free+0x4f/0x220 [ 21.022420] [] sk_free+0x2b/0x40 [ 21.027407] [] pppol2tp_release+0x239/0x2e0 [ 21.033349] [] sock_release+0x96/0x1c0 [ 21.038858] [] sock_close+0x16/0x20 [ 21.044109] [] __fput+0x263/0x700 [ 21.049201] [] ____fput+0x15/0x20 [ 21.054280] [] task_work_run+0x10c/0x180 [ 21.059975] [] exit_to_usermode_loop+0xfc/0x120 [ 21.066265] [] do_syscall_64+0x364/0x490 [ 21.071955] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.078856] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 21.105713] RIP [] l2tp_session_free+0x11c/0x200 [ 21.112221] RSP [ 21.115816] CR2: 0000000000000080 [ 21.119311] ---[ end trace 8cb807b5e1851584 ]--- [ 21.124070] Kernel panic - not syncing: Fatal exception [ 21.129784] Dumping ftrace buffer: [ 21.133303] (ftrace buffer empty) [ 21.136987] Kernel Offset: disabled [ 21.140580] Rebooting in 86400 seconds..