[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.350141] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.876769] random: sshd: uninitialized urandom read (32 bytes read) [ 21.231034] random: sshd: uninitialized urandom read (32 bytes read) [ 21.757515] random: sshd: uninitialized urandom read (32 bytes read) [ 24.119971] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.31' (ECDSA) to the list of known hosts. [ 29.687038] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.917890] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.926099] IP: [] l2tp_session_free+0x11c/0x200 [ 29.932531] PGD 1cd4ae067 [ 29.935168] PUD 1cd4af067 PMD 0 [ 29.938671] [ 29.940302] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.944766] Dumping ftrace buffer: [ 29.948277] (ftrace buffer empty) [ 29.951977] Modules linked in: [ 29.955259] CPU: 1 PID: 3806 Comm: syz-executor020 Not tainted 4.9.119-g9dc978d #75 [ 29.963025] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.972352] task: ffff8801b81ab000 task.stack: ffff8801b7678000 [ 29.978413] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 29.987274] RSP: 0018:ffff8801b767fca0 EFLAGS: 00010246 [ 29.992696] RAX: dffffc0000000000 RBX: ffff8801b7d47680 RCX: 0000000000000000 [ 29.999941] RDX: 1ffff10036ec66b0 RSI: ffffffff836bf9a1 RDI: ffff8801b7633580 [ 30.007199] RBP: ffff8801b767fcc0 R08: ffff8801b81ab8e8 R09: 0000000000000000 [ 30.014439] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7633400 [ 30.021681] R13: ffff8801b7d47688 R14: 0000000000000000 R15: ffffffff83015be0 [ 30.028926] FS: 0000000000e6b880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 30.037122] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.042975] CR2: 0000000000000080 CR3: 00000001c82a0000 CR4: 00000000001606f0 [ 30.050221] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.057472] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.064710] Stack: [ 30.066834] ffff8801b6f71100 ffff8801b7d47680 ffff8801b6f714d0 ffff8801b6f713d8 [ 30.074864] ffff8801b767fce8 ffffffff836c72b2 ffff8801b6f71540 ffff8801b6f71100 [ 30.082856] ffffffff836c71e0 ffff8801b767fd20 ffffffff830230f5 ffff8801b6f71540 [ 30.090857] Call Trace: [ 30.093415] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.100070] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.106360] [] __sk_destruct+0x55/0x590 [ 30.111962] [] ? sock_release+0x1c0/0x1c0 [ 30.117735] [] sk_destruct+0x63/0x80 [ 30.123071] [] __sk_free+0x4f/0x220 [ 30.128336] [] sk_free+0x2b/0x40 [ 30.133320] [] pppol2tp_release+0x239/0x2e0 [ 30.139261] [] sock_release+0x96/0x1c0 [ 30.144784] [] sock_close+0x16/0x20 [ 30.150035] [] __fput+0x263/0x700 [ 30.155110] [] ____fput+0x15/0x20 [ 30.160192] [] task_work_run+0x10c/0x180 [ 30.165875] [] exit_to_usermode_loop+0xfc/0x120 [ 30.172165] [] do_syscall_64+0x364/0x490 [ 30.177848] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.184754] 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 [ 30.211563] RIP [] l2tp_session_free+0x11c/0x200 [ 30.218057] RSP [ 30.221683] CR2: 0000000000000080 [ 30.225189] ---[ end trace 928f3cd1de5b77ac ]--- [ 30.229952] Kernel panic - not syncing: Fatal exception [ 30.235671] Dumping ftrace buffer: [ 30.239186] (ftrace buffer empty) [ 30.242868] Kernel Offset: disabled [ 30.246463] Rebooting in 86400 seconds..