[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.299036] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.761822] random: sshd: uninitialized urandom read (32 bytes read) [ 15.170287] random: sshd: uninitialized urandom read (32 bytes read) [ 15.654176] random: sshd: uninitialized urandom read (32 bytes read) [ 15.793807] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.32' (ECDSA) to the list of known hosts. [ 21.528699] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.751445] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.759841] IP: [] l2tp_session_free+0x11c/0x200 [ 21.766260] PGD 1caf9b067 [ 21.768929] PUD 1c1b7d067 PMD 0 [ 21.772419] [ 21.774037] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.778519] Dumping ftrace buffer: [ 21.782031] (ftrace buffer empty) [ 21.785713] Modules linked in: [ 21.789010] CPU: 1 PID: 3699 Comm: syz-executor294 Not tainted 4.9.122-g54068d6 #78 [ 21.796789] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.806125] task: ffff8801c2780000 task.stack: ffff8801c0840000 [ 21.812158] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.821015] RSP: 0018:ffff8801c0847ca0 EFLAGS: 00010246 [ 21.826456] RAX: dffffc0000000000 RBX: ffff8801c0c9af00 RCX: 0000000000000000 [ 21.833810] RDX: 1ffff10038217e10 RSI: ffffffff836c39a1 RDI: ffff8801c10bf080 [ 21.841063] RBP: ffff8801c0847cc0 R08: ffff8801c27808e8 R09: 0000000000000000 [ 21.848313] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c10bef00 [ 21.855563] R13: ffff8801c0c9af08 R14: 0000000000000000 R15: ffffffff83019be0 [ 21.862814] FS: 00000000017fd880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.871021] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.876883] CR2: 0000000000000080 CR3: 00000001c72be000 CR4: 00000000001606f0 [ 21.884248] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.891495] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.898738] Stack: [ 21.900862] ffff8801c1616e80 ffff8801c0c9af00 ffff8801c1617250 ffff8801c1617158 [ 21.908952] ffff8801c0847ce8 ffffffff836cb2b2 ffff8801c16172c0 ffff8801c1616e80 [ 21.916948] ffffffff836cb1e0 ffff8801c0847d20 ffffffff830270f5 ffff8801c16172c0 [ 21.925069] Call Trace: [ 21.927653] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.934294] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.940588] [] __sk_destruct+0x55/0x590 [ 21.946184] [] ? sock_release+0x1c0/0x1c0 [ 21.951958] [] sk_destruct+0x63/0x80 [ 21.957451] [] __sk_free+0x4f/0x220 [ 21.962853] [] sk_free+0x2b/0x40 [ 21.967851] [] pppol2tp_release+0x239/0x2e0 [ 21.973802] [] sock_release+0x96/0x1c0 [ 21.979336] [] sock_close+0x16/0x20 [ 21.984662] [] __fput+0x263/0x700 [ 21.989748] [] ____fput+0x15/0x20 [ 21.994832] [] task_work_run+0x10c/0x180 [ 22.000525] [] exit_to_usermode_loop+0xfc/0x120 [ 22.006824] [] do_syscall_64+0x364/0x490 [ 22.012528] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.019422] 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 [ 22.046436] RIP [] l2tp_session_free+0x11c/0x200 [ 22.052957] RSP [ 22.056555] CR2: 0000000000000080 [ 22.060167] ---[ end trace 85896787763cf43a ]--- [ 22.064955] Kernel panic - not syncing: Fatal exception [ 22.070654] Dumping ftrace buffer: [ 22.074182] (ftrace buffer empty) [ 22.077871] Kernel Offset: disabled [ 22.081475] Rebooting in 86400 seconds..