[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.909264] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.132685] random: sshd: uninitialized urandom read (32 bytes read) [ 18.370705] random: sshd: uninitialized urandom read (32 bytes read) [ 18.866347] random: sshd: uninitialized urandom read (32 bytes read) [ 24.397774] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.43' (ECDSA) to the list of known hosts. [ 29.843193] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.041933] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.050144] IP: [] l2tp_session_free+0x11c/0x200 [ 30.056665] PGD 1c6f09067 [ 30.059309] PUD 1c1aa7067 PMD 0 [ 30.062790] [ 30.064421] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.068889] Dumping ftrace buffer: [ 30.072399] (ftrace buffer empty) [ 30.076082] Modules linked in: [ 30.079366] CPU: 0 PID: 3803 Comm: syz-executor171 Not tainted 4.9.118-g47b77b8 #20 [ 30.087133] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.096466] task: ffff8801b601b000 task.stack: ffff8801d9510000 [ 30.102499] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.111350] RSP: 0018:ffff8801d9517ca0 EFLAGS: 00010246 [ 30.116775] RAX: dffffc0000000000 RBX: ffff8801b6051400 RCX: 0000000000000000 [ 30.124021] RDX: 1ffff10036ca93a0 RSI: ffffffff836bf781 RDI: ffff8801b6549d00 [ 30.131265] RBP: ffff8801d9517cc0 R08: ffff8801b601b8e8 R09: 0000000000000000 [ 30.138509] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6549b80 [ 30.145750] R13: ffff8801b6051408 R14: 0000000000000000 R15: ffffffff83015be0 [ 30.152994] FS: 0000000001a01880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 30.161193] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.167047] CR2: 0000000000000080 CR3: 00000001be679000 CR4: 00000000001606f0 [ 30.174291] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.181533] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.188839] Stack: [ 30.190968] ffff8801b60f7700 ffff8801b6051400 ffff8801b60f7ad0 ffff8801b60f79d8 [ 30.198953] ffff8801d9517ce8 ffffffff836c7092 ffff8801b60f7b40 ffff8801b60f7700 [ 30.206945] ffffffff836c6fc0 ffff8801d9517d20 ffffffff830230f5 ffff8801b60f7b40 [ 30.214940] Call Trace: [ 30.217506] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.224216] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.230597] [] __sk_destruct+0x55/0x590 [ 30.236204] [] ? sock_release+0x1c0/0x1c0 [ 30.241977] [] sk_destruct+0x63/0x80 [ 30.247316] [] __sk_free+0x4f/0x220 [ 30.252570] [] sk_free+0x2b/0x40 [ 30.257562] [] pppol2tp_release+0x239/0x2e0 [ 30.263519] [] sock_release+0x96/0x1c0 [ 30.269032] [] sock_close+0x16/0x20 [ 30.274285] [] __fput+0x263/0x700 [ 30.279367] [] ____fput+0x15/0x20 [ 30.284448] [] task_work_run+0x10c/0x180 [ 30.290139] [] exit_to_usermode_loop+0xfc/0x120 [ 30.296434] [] do_syscall_64+0x364/0x490 [ 30.302123] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.309019] 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 f2 c9 fd 4c 89 ea 48 b8 00 [ 30.335915] RIP [] l2tp_session_free+0x11c/0x200 [ 30.342416] RSP [ 30.346016] CR2: 0000000000000080 [ 30.350928] ---[ end trace 95564fdddc10c1ca ]--- [ 30.355681] Kernel panic - not syncing: Fatal exception [ 30.361373] Dumping ftrace buffer: [ 30.364890] (ftrace buffer empty) [ 30.368570] Kernel Offset: disabled [ 30.372169] Rebooting in 86400 seconds..