[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.445053] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.885801] random: sshd: uninitialized urandom read (32 bytes read) [ 26.331509] random: sshd: uninitialized urandom read (32 bytes read) [ 26.765812] random: sshd: uninitialized urandom read (32 bytes read) [ 26.895895] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.50' (ECDSA) to the list of known hosts. [ 32.496045] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 32.700854] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 32.709162] IP: [] l2tp_session_free+0x11c/0x200 [ 32.715587] PGD 1cb40f067 [ 32.718226] PUD 1ca8c6067 PMD 0 [ 32.721704] [ 32.723323] Oops: 0002 [#1] PREEMPT SMP KASAN [ 32.727789] Dumping ftrace buffer: [ 32.731303] (ftrace buffer empty) [ 32.734989] Modules linked in: [ 32.738274] CPU: 1 PID: 3789 Comm: syz-executor505 Not tainted 4.9.122-g54068d6 #26 [ 32.746078] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.755411] task: ffff8801bc76e000 task.stack: ffff8801b98a8000 [ 32.761444] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 32.770298] RSP: 0018:ffff8801b98afca0 EFLAGS: 00010246 [ 32.775717] RAX: dffffc0000000000 RBX: ffff8801c65cd900 RCX: 0000000000000000 [ 32.782965] RDX: 1ffff10038ce3f50 RSI: ffffffff836c39a1 RDI: ffff8801c671fa80 [ 32.790209] RBP: ffff8801b98afcc0 R08: ffff8801bc76e8e8 R09: 0000000000000000 [ 32.797451] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c671f900 [ 32.804698] R13: ffff8801c65cd908 R14: 0000000000000000 R15: ffffffff83019be0 [ 32.811943] FS: 0000000000dac880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 32.820139] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 32.826094] CR2: 0000000000000080 CR3: 00000001caded000 CR4: 00000000001606f0 [ 32.833342] Stack: [ 32.835471] ffff8801b9ec5d80 ffff8801c65cd900 ffff8801b9ec6150 ffff8801b9ec6058 [ 32.843457] ffff8801b98afce8 ffffffff836cb2b2 ffff8801b9ec61c0 ffff8801b9ec5d80 [ 32.851496] ffffffff836cb1e0 ffff8801b98afd20 ffffffff830270f5 ffff8801b9ec61c0 [ 32.859483] Call Trace: [ 32.862051] [] pppol2tp_session_destruct+0xd2/0x110 [ 32.868699] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 32.875000] [] __sk_destruct+0x55/0x590 [ 32.880599] [] ? sock_release+0x1c0/0x1c0 [ 32.886455] [] sk_destruct+0x63/0x80 [ 32.891855] [] __sk_free+0x4f/0x220 [ 32.897111] [] sk_free+0x2b/0x40 [ 32.902100] [] pppol2tp_release+0x239/0x2e0 [ 32.908046] [] sock_release+0x96/0x1c0 [ 32.913555] [] sock_close+0x16/0x20 [ 32.918809] [] __fput+0x263/0x700 [ 32.923893] [] ____fput+0x15/0x20 [ 32.928979] [] task_work_run+0x10c/0x180 [ 32.934666] [] exit_to_usermode_loop+0xfc/0x120 [ 32.940960] [] do_syscall_64+0x364/0x490 [ 32.946647] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.953544] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 32.980456] RIP [] l2tp_session_free+0x11c/0x200 [ 32.987088] RSP [ 32.990690] CR2: 0000000000000080 [ 32.994256] ---[ end trace 5250963ac4963042 ]--- [ 32.999002] Kernel panic - not syncing: Fatal exception [ 33.004613] Dumping ftrace buffer: [ 33.008132] (ftrace buffer empty) [ 33.011864] Kernel Offset: disabled [ 33.015473] Rebooting in 86400 seconds..