[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.893068] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.232683] random: sshd: uninitialized urandom read (32 bytes read) [ 18.675514] random: sshd: uninitialized urandom read (32 bytes read) [ 19.183610] random: sshd: uninitialized urandom read (32 bytes read) [ 19.328680] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.33' (ECDSA) to the list of known hosts. [ 25.066983] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.264302] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.272544] IP: [] l2tp_session_free+0x11c/0x200 [ 25.278977] PGD 1bdb92067 [ 25.281621] PUD 1bda03067 PMD 0 [ 25.285092] [ 25.286722] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.291304] Dumping ftrace buffer: [ 25.294818] (ftrace buffer empty) [ 25.298508] Modules linked in: [ 25.301800] CPU: 0 PID: 3789 Comm: syz-executor850 Not tainted 4.9.123-g8dd3fc2 #27 [ 25.309565] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.318944] task: ffff8801bab56000 task.stack: ffff8801b8020000 [ 25.324987] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.333832] RSP: 0018:ffff8801b8027ca0 EFLAGS: 00010246 [ 25.339305] RAX: dffffc0000000000 RBX: ffff8801b84cb400 RCX: 0000000000000000 [ 25.346552] RDX: 1ffff10037099700 RSI: ffffffff836c4991 RDI: ffff8801b84cb800 [ 25.353848] RBP: ffff8801b8027cc0 R08: ffff8801bab568e8 R09: 0000000000000000 [ 25.361095] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b84cb680 [ 25.368340] R13: ffff8801b84cb408 R14: 0000000000000000 R15: ffffffff8301abe0 [ 25.375822] FS: 0000000000de0880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.384304] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.390171] CR2: 0000000000000080 CR3: 00000001beec2000 CR4: 00000000001606f0 [ 25.397415] Stack: [ 25.399536] ffff8801da371100 ffff8801b84cb400 ffff8801da3714d0 ffff8801da3713d8 [ 25.407554] ffff8801b8027ce8 ffffffff836cc2a2 ffff8801da371540 ffff8801da371100 [ 25.415633] ffffffff836cc1d0 ffff8801b8027d20 ffffffff830280f5 ffff8801da371540 [ 25.423630] Call Trace: [ 25.426190] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.432827] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.439121] [] __sk_destruct+0x55/0x590 [ 25.444723] [] ? sock_release+0x1c0/0x1c0 [ 25.450496] [] sk_destruct+0x63/0x80 [ 25.455847] [] __sk_free+0x4f/0x220 [ 25.461098] [] sk_free+0x2b/0x40 [ 25.466185] [] pppol2tp_release+0x239/0x2e0 [ 25.472141] [] sock_release+0x96/0x1c0 [ 25.477650] [] sock_close+0x16/0x20 [ 25.482897] [] __fput+0x263/0x700 [ 25.488074] [] ____fput+0x15/0x20 [ 25.493149] [] task_work_run+0x10c/0x180 [ 25.498846] [] exit_to_usermode_loop+0xfc/0x120 [ 25.505141] [] do_syscall_64+0x364/0x490 [ 25.510831] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.517726] 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 e5 c3 c9 fd 4c 89 ea 48 b8 00 [ 25.544776] RIP [] l2tp_session_free+0x11c/0x200 [ 25.551276] RSP [ 25.554874] CR2: 0000000000000080 [ 25.559364] ---[ end trace 74afb4d1fcc50118 ]--- [ 25.564102] Kernel panic - not syncing: Fatal exception [ 25.569731] Dumping ftrace buffer: [ 25.573249] (ftrace buffer empty) [ 25.576934] Kernel Offset: disabled [ 25.580531] Rebooting in 86400 seconds..