[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.303379] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 15.565028] random: sshd: uninitialized urandom read (32 bytes read) [ 15.776933] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 31.820916] urandom_read: 1 callbacks suppressed [ 31.820918] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.22' (ECDSA) to the list of known hosts. [ 37.230415] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 37.421334] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 37.429553] IP: [] l2tp_session_free+0x11c/0x200 [ 37.435963] PGD 1b6e1a067 [ 37.438602] PUD 1b6e1b067 PMD 0 [ 37.442088] [ 37.443706] Oops: 0002 [#1] PREEMPT SMP KASAN [ 37.448170] Dumping ftrace buffer: [ 37.451677] (ftrace buffer empty) [ 37.455359] Modules linked in: [ 37.458643] CPU: 0 PID: 3809 Comm: syz-executor212 Not tainted 4.9.117-g8b21e85 #19 [ 37.466404] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.475729] task: ffff8801b7260000 task.stack: ffff8801d9268000 [ 37.481762] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 37.490614] RSP: 0018:ffff8801d926fca0 EFLAGS: 00010246 [ 37.496033] RAX: dffffc0000000000 RBX: ffff8801c9c2bb80 RCX: 0000000000000000 [ 37.503274] RDX: 1ffff10036dea4d0 RSI: ffffffff836bf8f1 RDI: ffff8801b6f52680 [ 37.510515] RBP: ffff8801d926fcc0 R08: ffff8801b72608e8 R09: 0000000000000000 [ 37.517760] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6f52500 [ 37.525001] R13: ffff8801c9c2bb88 R14: 0000000000000000 R15: ffffffff83015be0 [ 37.532246] FS: 000000000217f880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 37.540451] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 37.546307] CR2: 0000000000000080 CR3: 00000001b6eb3000 CR4: 00000000001606f0 [ 37.553563] Stack: [ 37.555687] ffff8801d9884400 ffff8801c9c2bb80 ffff8801d98847d0 ffff8801d98846d8 [ 37.563664] ffff8801d926fce8 ffffffff836c7202 ffff8801d9884840 ffff8801d9884400 [ 37.571657] ffffffff836c7130 ffff8801d926fd20 ffffffff83023095 ffff8801d9884840 [ 37.579647] Call Trace: [ 37.582208] [] pppol2tp_session_destruct+0xd2/0x110 [ 37.588849] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 37.595148] [] __sk_destruct+0x55/0x590 [ 37.600744] [] ? sock_release+0x1c0/0x1c0 [ 37.606515] [] sk_destruct+0x63/0x80 [ 37.611852] [] __sk_free+0x4f/0x220 [ 37.617100] [] sk_free+0x2b/0x40 [ 37.622086] [] pppol2tp_release+0x239/0x2e0 [ 37.628028] [] sock_release+0x96/0x1c0 [ 37.633573] [] sock_close+0x16/0x20 [ 37.638826] [] __fput+0x263/0x700 [ 37.643903] [] ____fput+0x15/0x20 [ 37.648980] [] task_work_run+0x10c/0x180 [ 37.654664] [] exit_to_usermode_loop+0xfc/0x120 [ 37.660953] [] do_syscall_64+0x364/0x490 [ 37.666638] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.673532] 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 [ 37.700370] RIP [] l2tp_session_free+0x11c/0x200 [ 37.706872] RSP [ 37.710468] CR2: 0000000000000080 [ 37.714150] ---[ end trace a883b81cdd0b44ef ]--- [ 37.718950] Kernel panic - not syncing: Fatal exception [ 37.724561] Dumping ftrace buffer: [ 37.728077] (ftrace buffer empty) [ 37.731760] Kernel Offset: disabled [ 37.735357] Rebooting in 86400 seconds..