[....] 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[ 15.620807] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.825697] random: sshd: uninitialized urandom read (32 bytes read) [ 18.121598] random: sshd: uninitialized urandom read (32 bytes read) [ 18.622119] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.200' (ECDSA) to the list of known hosts. [ 24.227098] urandom_read: 1 callbacks suppressed [ 24.227102] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.440531] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.448769] IP: [] l2tp_session_free+0x11c/0x200 [ 24.455179] PGD 1c9c6b067 [ 24.457818] PUD 1c9c6a067 PMD 0 [ 24.461287] [ 24.462906] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.467370] Dumping ftrace buffer: [ 24.470878] (ftrace buffer empty) [ 24.474556] Modules linked in: [ 24.477838] CPU: 0 PID: 3802 Comm: syz-executor688 Not tainted 4.9.117-g8b21e85 #71 [ 24.485600] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.494964] task: ffff8801b7798000 task.stack: ffff8801b5d18000 [ 24.500989] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.509831] RSP: 0018:ffff8801b5d1fca0 EFLAGS: 00010246 [ 24.515261] RAX: dffffc0000000000 RBX: ffff8801b5cdaf00 RCX: 0000000000000000 [ 24.522501] RDX: 1ffff10036d01830 RSI: ffffffff836bf8f1 RDI: ffff8801b680c180 [ 24.529741] RBP: ffff8801b5d1fcc0 R08: ffff8801b77988e8 R09: 0000000000000000 [ 24.536983] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b680c000 [ 24.544223] R13: ffff8801b5cdaf08 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.551464] FS: 0000000002480880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.559660] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.565510] CR2: 0000000000000080 CR3: 00000001b6ca4000 CR4: 00000000001606f0 [ 24.572764] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.580003] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.587252] Stack: [ 24.589374] ffff8801b629a200 ffff8801b5cdaf00 ffff8801b629a5d0 ffff8801b629a4d8 [ 24.597402] ffff8801b5d1fce8 ffffffff836c7202 ffff8801b629a640 ffff8801b629a200 [ 24.605412] ffffffff836c7130 ffff8801b5d1fd20 ffffffff83023095 ffff8801b629a640 [ 24.613384] Call Trace: [ 24.615945] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.622581] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.628871] [] __sk_destruct+0x55/0x590 [ 24.634474] [] ? sock_release+0x1c0/0x1c0 [ 24.640248] [] sk_destruct+0x63/0x80 [ 24.645583] [] __sk_free+0x4f/0x220 [ 24.650826] [] sk_free+0x2b/0x40 [ 24.655810] [] pppol2tp_release+0x239/0x2e0 [ 24.661844] [] sock_release+0x96/0x1c0 [ 24.667350] [] sock_close+0x16/0x20 [ 24.672596] [] __fput+0x263/0x700 [ 24.677760] [] ____fput+0x15/0x20 [ 24.682840] [] task_work_run+0x10c/0x180 [ 24.688523] [] exit_to_usermode_loop+0xfc/0x120 [ 24.694812] [] do_syscall_64+0x364/0x490 [ 24.700493] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.707386] 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 f1 c9 fd 4c 89 ea 48 b8 00 [ 24.734069] RIP [] l2tp_session_free+0x11c/0x200 [ 24.740569] RSP [ 24.744168] CR2: 0000000000000080 [ 24.747803] ---[ end trace 12f177a91d106010 ]--- [ 24.752553] Kernel panic - not syncing: Fatal exception [ 24.758175] Dumping ftrace buffer: [ 24.761693] (ftrace buffer empty) [ 24.765373] Kernel Offset: disabled [ 24.768975] Rebooting in 86400 seconds..