[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.805643] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.970356] random: sshd: uninitialized urandom read (32 bytes read) [ 16.234239] random: sshd: uninitialized urandom read (32 bytes read) [ 17.194438] random: sshd: uninitialized urandom read (32 bytes read) [ 17.342265] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.34' (ECDSA) to the list of known hosts. [ 22.820949] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.038485] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.046803] IP: [] l2tp_session_free+0x11c/0x200 [ 23.053247] PGD 1c260f067 [ 23.055898] PUD 1c2614067 PMD 0 [ 23.059391] [ 23.061020] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.065507] Dumping ftrace buffer: [ 23.069040] (ftrace buffer empty) [ 23.072742] Modules linked in: [ 23.076030] CPU: 1 PID: 3800 Comm: syz-executor089 Not tainted 4.9.113-g47bbcd6 #10 [ 23.083801] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.093159] task: ffff8801b7363000 task.stack: ffff8801d9b78000 [ 23.099209] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.108106] RSP: 0018:ffff8801d9b7fca0 EFLAGS: 00010246 [ 23.113538] RAX: dffffc0000000000 RBX: ffff8801b5c5f900 RCX: 0000000000000000 [ 23.120795] RDX: 1ffff100394abab0 RSI: ffffffff836bcce1 RDI: ffff8801ca55d580 [ 23.128056] RBP: ffff8801d9b7fcc0 R08: ffff8801b73638e8 R09: 0000000000000000 [ 23.135315] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca55d400 [ 23.142596] R13: ffff8801b5c5f908 R14: 0000000000000000 R15: ffffffff83013be0 [ 23.150814] FS: 00000000018d5880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 23.159054] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.164926] CR2: 0000000000000080 CR3: 00000001c6d1f000 CR4: 00000000001606f0 [ 23.172195] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.179466] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.186731] Stack: [ 23.188873] ffff8801b632d500 ffff8801b5c5f900 ffff8801b632d8d0 ffff8801b632d7d8 [ 23.197172] ffff8801d9b7fce8 ffffffff836c45f2 ffff8801b632d940 ffff8801b632d500 [ 23.205213] ffffffff836c4520 ffff8801d9b7fd20 ffffffff83021095 ffff8801b632d940 [ 23.213260] Call Trace: [ 23.215838] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.222498] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.228815] [] __sk_destruct+0x55/0x590 [ 23.234424] [] ? sock_release+0x1c0/0x1c0 [ 23.240215] [] sk_destruct+0x63/0x80 [ 23.245588] [] __sk_free+0x4f/0x220 [ 23.250847] [] sk_free+0x2b/0x40 [ 23.255876] [] pppol2tp_release+0x239/0x2e0 [ 23.261856] [] sock_release+0x96/0x1c0 [ 23.267406] [] sock_close+0x16/0x20 [ 23.272697] [] __fput+0x263/0x700 [ 23.277809] [] ____fput+0x15/0x20 [ 23.282915] [] task_work_run+0x10c/0x180 [ 23.288621] [] exit_to_usermode_loop+0xfc/0x120 [ 23.294953] [] do_syscall_64+0x364/0x490 [ 23.300658] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.307584] 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 1d ca fd 4c 89 ea 48 b8 00 [ 23.334971] RIP [] l2tp_session_free+0x11c/0x200 [ 23.341503] RSP [ 23.345122] CR2: 0000000000000080 [ 23.348648] ---[ end trace fcc314d7b645214e ]--- [ 23.353412] Kernel panic - not syncing: Fatal exception [ 23.359315] Dumping ftrace buffer: [ 23.362843] (ftrace buffer empty) [ 23.366590] Kernel Offset: disabled [ 23.370240] Rebooting in 86400 seconds..