[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.515050] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 31.865298] random: sshd: uninitialized urandom read (32 bytes read) [ 32.222123] random: sshd: uninitialized urandom read (32 bytes read) [ 32.847765] random: sshd: uninitialized urandom read (32 bytes read) [ 32.978746] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.23' (ECDSA) to the list of known hosts. [ 38.362999] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 38.551330] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 38.559592] IP: [] l2tp_session_free+0x11c/0x200 [ 38.566027] PGD 1c8ac9067 [ 38.568676] PUD 1c8b64067 PMD 0 [ 38.572168] [ 38.573803] Oops: 0002 [#1] PREEMPT SMP KASAN [ 38.578274] Dumping ftrace buffer: [ 38.581827] (ftrace buffer empty) [ 38.585518] Modules linked in: [ 38.588829] CPU: 0 PID: 3764 Comm: syz-executor095 Not tainted 4.9.113-g9905591 #66 [ 38.596606] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.605952] task: ffff8801bdd60000 task.stack: ffff8801da3a8000 [ 38.611989] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 38.620853] RSP: 0018:ffff8801da3afca0 EFLAGS: 00010246 [ 38.626293] RAX: dffffc0000000000 RBX: ffff8801c8828c80 RCX: 0000000000000000 [ 38.633557] RDX: 1ffff1003969ec30 RSI: ffffffff836bcee1 RDI: ffff8801cb4f6180 [ 38.640808] RBP: ffff8801da3afcc0 R08: ffff8801bdd608e8 R09: 0000000000000000 [ 38.648076] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb4f6000 [ 38.655322] R13: ffff8801c8828c88 R14: 0000000000000000 R15: ffffffff83013be0 [ 38.662571] FS: 0000000000d27880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 38.670775] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 38.676645] CR2: 0000000000000080 CR3: 00000001c9465000 CR4: 00000000001606f0 [ 38.683898] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 38.691150] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 38.698405] Stack: [ 38.700535] ffff8801bbc4cc80 ffff8801c8828c80 ffff8801bbc4d050 ffff8801bbc4cf58 [ 38.708593] ffff8801da3afce8 ffffffff836c47f2 ffff8801bbc4d0c0 ffff8801bbc4cc80 [ 38.716626] ffffffff836c4720 ffff8801da3afd20 ffffffff83021095 ffff8801bbc4d0c0 [ 38.724667] Call Trace: [ 38.727240] [] pppol2tp_session_destruct+0xd2/0x110 [ 38.733887] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 38.740187] [] __sk_destruct+0x55/0x590 [ 38.745792] [] ? sock_release+0x1c0/0x1c0 [ 38.751570] [] sk_destruct+0x63/0x80 [ 38.756934] [] __sk_free+0x4f/0x220 [ 38.762197] [] sk_free+0x2b/0x40 [ 38.767192] [] pppol2tp_release+0x239/0x2e0 [ 38.773152] [] sock_release+0x96/0x1c0 [ 38.778668] [] sock_close+0x16/0x20 [ 38.783929] [] __fput+0x263/0x700 [ 38.789011] [] ____fput+0x15/0x20 [ 38.794092] [] task_work_run+0x10c/0x180 [ 38.799787] [] exit_to_usermode_loop+0xfc/0x120 [ 38.806088] [] do_syscall_64+0x364/0x490 [ 38.811784] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 38.818688] 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 1b ca fd 4c 89 ea 48 b8 00 [ 38.845996] RIP [] l2tp_session_free+0x11c/0x200 [ 38.852511] RSP [ 38.856115] CR2: 0000000000000080 [ 38.859811] ---[ end trace b881b3777925c9fe ]--- [ 38.864570] Kernel panic - not syncing: Fatal exception [ 38.870424] Dumping ftrace buffer: [ 38.874034] (ftrace buffer empty) [ 38.877809] Kernel Offset: disabled [ 38.881415] Rebooting in 86400 seconds..