[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.779945] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 30.415008] random: sshd: uninitialized urandom read (32 bytes read) [ 30.682882] random: sshd: uninitialized urandom read (32 bytes read) [ 31.235182] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.26' (ECDSA) to the list of known hosts. [ 36.947216] urandom_read: 1 callbacks suppressed [ 36.947219] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 37.165521] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 37.173743] IP: [] l2tp_session_free+0x11c/0x200 [ 37.180163] PGD 1c9ac9067 [ 37.182802] PUD 1b85e6067 PMD 0 [ 37.186279] [ 37.187900] Oops: 0002 [#1] PREEMPT SMP KASAN [ 37.192367] Dumping ftrace buffer: [ 37.195927] (ftrace buffer empty) [ 37.199618] Modules linked in: [ 37.202919] CPU: 1 PID: 3814 Comm: syz-executor201 Not tainted 4.9.120-gf85543b #24 [ 37.210693] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.220480] task: ffff8801bdc6c800 task.stack: ffff8801b5ec0000 [ 37.226509] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 37.235419] RSP: 0018:ffff8801b5ec7ca0 EFLAGS: 00010246 [ 37.240842] RAX: dffffc0000000000 RBX: ffff8801b5f0c000 RCX: 0000000000000000 [ 37.248089] RDX: 1ffff10036bb0a10 RSI: ffffffff836c29a1 RDI: ffff8801b5d85080 [ 37.255422] RBP: ffff8801b5ec7cc0 R08: ffff8801bdc6d0e8 R09: 0000000000000000 [ 37.262667] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5d84f00 [ 37.269911] R13: ffff8801b5f0c008 R14: 0000000000000000 R15: ffffffff83018be0 [ 37.277158] FS: 0000000001ea5880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 37.285404] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 37.291269] CR2: 0000000000000080 CR3: 00000001c9acb000 CR4: 00000000001606f0 [ 37.298512] Stack: [ 37.300641] ffff8801b791c400 ffff8801b5f0c000 ffff8801b791c7d0 ffff8801b791c6d8 [ 37.308681] ffff8801b5ec7ce8 ffffffff836ca2b2 ffff8801b791c840 ffff8801b791c400 [ 37.316672] ffffffff836ca1e0 ffff8801b5ec7d20 ffffffff830260f5 ffff8801b791c840 [ 37.324655] Call Trace: [ 37.327222] [] pppol2tp_session_destruct+0xd2/0x110 [ 37.333861] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 37.340154] [] __sk_destruct+0x55/0x590 [ 37.345796] [] ? sock_release+0x1c0/0x1c0 [ 37.351576] [] sk_destruct+0x63/0x80 [ 37.356919] [] __sk_free+0x4f/0x220 [ 37.362172] [] sk_free+0x2b/0x40 [ 37.367165] [] pppol2tp_release+0x239/0x2e0 [ 37.373109] [] sock_release+0x96/0x1c0 [ 37.378878] [] sock_close+0x16/0x20 [ 37.384132] [] __fput+0x263/0x700 [ 37.389208] [] ____fput+0x15/0x20 [ 37.394425] [] task_work_run+0x10c/0x180 [ 37.400114] [] exit_to_usermode_loop+0xfc/0x120 [ 37.406408] [] do_syscall_64+0x364/0x490 [ 37.412100] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.418999] 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 15 de c9 fd 4c 89 ea 48 b8 00 [ 37.445897] RIP [] l2tp_session_free+0x11c/0x200 [ 37.452399] RSP [ 37.455996] CR2: 0000000000000080 [ 37.459660] ---[ end trace 09297f7a20d1e38a ]--- [ 37.464400] Kernel panic - not syncing: Fatal exception [ 37.470018] Dumping ftrace buffer: [ 37.473538] (ftrace buffer empty) [ 37.477221] Kernel Offset: disabled [ 37.480822] Rebooting in 86400 seconds..