[....] 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[ 13.060637] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.962526] random: sshd: uninitialized urandom read (32 bytes read) [ 28.406419] random: sshd: uninitialized urandom read (32 bytes read) [ 28.798853] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.6' (ECDSA) to the list of known hosts. [ 34.447829] urandom_read: 1 callbacks suppressed [ 34.447832] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.647705] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.655955] IP: [] l2tp_session_free+0x11c/0x200 [ 34.662378] PGD 1c7832067 [ 34.665021] PUD 1c7b3d067 PMD 0 [ 34.668619] [ 34.670242] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.674713] Dumping ftrace buffer: [ 34.678271] (ftrace buffer empty) [ 34.681965] Modules linked in: [ 34.685259] CPU: 0 PID: 3662 Comm: syz-executor292 Not tainted 4.9.123-g8dd3fc2 #79 [ 34.693024] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.702462] task: ffff8801c3cfc800 task.stack: ffff8801c5a30000 [ 34.708540] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.717406] RSP: 0018:ffff8801c5a37ca0 EFLAGS: 00010246 [ 34.722835] RAX: dffffc0000000000 RBX: ffff8801c3cd2280 RCX: 0000000000000000 [ 34.730171] RDX: 1ffff100393bbf00 RSI: ffffffff836c4991 RDI: ffff8801c9ddf800 [ 34.737417] RBP: ffff8801c5a37cc0 R08: ffff8801c3cfd0e8 R09: 0000000000000000 [ 34.744672] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9ddf680 [ 34.751959] R13: ffff8801c3cd2288 R14: 0000000000000000 R15: ffffffff8301abe0 [ 34.759214] FS: 0000000000fd2880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.767419] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.773285] CR2: 0000000000000080 CR3: 00000001c4334000 CR4: 00000000001606f0 [ 34.780532] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.787782] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.795068] Stack: [ 34.797197] ffff8801c3da2a80 ffff8801c3cd2280 ffff8801c3da2e50 ffff8801c3da2d58 [ 34.805176] ffff8801c5a37ce8 ffffffff836cc2a2 ffff8801c3da2ec0 ffff8801c3da2a80 [ 34.813172] ffffffff836cc1d0 ffff8801c5a37d20 ffffffff830280f5 ffff8801c3da2ec0 [ 34.821170] Call Trace: [ 34.823745] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.830393] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.836735] [] __sk_destruct+0x55/0x590 [ 34.842349] [] ? sock_release+0x1c0/0x1c0 [ 34.848135] [] sk_destruct+0x63/0x80 [ 34.853480] [] __sk_free+0x4f/0x220 [ 34.858887] [] sk_free+0x2b/0x40 [ 34.863887] [] pppol2tp_release+0x239/0x2e0 [ 34.869834] [] sock_release+0x96/0x1c0 [ 34.875353] [] sock_close+0x16/0x20 [ 34.880609] [] __fput+0x263/0x700 [ 34.885732] [] ____fput+0x15/0x20 [ 34.890819] [] task_work_run+0x10c/0x180 [ 34.896511] [] exit_to_usermode_loop+0xfc/0x120 [ 34.902808] [] do_syscall_64+0x364/0x490 [ 34.908563] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.915464] 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 [ 34.942563] RIP [] l2tp_session_free+0x11c/0x200 [ 34.949076] RSP [ 34.952679] CR2: 0000000000000080 [ 34.956610] ---[ end trace 4a467ea230c66450 ]--- [ 34.961392] Kernel panic - not syncing: Fatal exception [ 34.967071] Dumping ftrace buffer: [ 34.970595] (ftrace buffer empty) [ 34.974284] Kernel Offset: disabled [ 34.978000] Rebooting in 86400 seconds..