[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.717480] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 24.071964] random: sshd: uninitialized urandom read (32 bytes read) [ 24.448295] random: sshd: uninitialized urandom read (32 bytes read) [ 25.170144] random: sshd: uninitialized urandom read (32 bytes read) [ 25.295389] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.32' (ECDSA) to the list of known hosts. [ 30.700176] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.910898] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.919260] IP: [] l2tp_session_free+0x11c/0x200 [ 30.925713] PGD 1b66ed067 [ 30.928360] PUD 1b7526067 PMD 0 [ 30.931874] [ 30.933509] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.937992] Dumping ftrace buffer: [ 30.941523] (ftrace buffer empty) [ 30.945231] Modules linked in: [ 30.948676] CPU: 1 PID: 3808 Comm: syz-executor029 Not tainted 4.9.113-g8956c50 #15 [ 30.956462] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.965900] task: ffff8801b74be000 task.stack: ffff8801d95b8000 [ 30.972038] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.981042] RSP: 0018:ffff8801d95bfca0 EFLAGS: 00010246 [ 30.986749] RAX: dffffc0000000000 RBX: ffff8801b5516780 RCX: 0000000000000000 [ 30.994057] RDX: 1ffff1003b338ba0 RSI: ffffffff836bcee1 RDI: ffff8801d99c5d00 [ 31.001330] RBP: ffff8801d95bfcc0 R08: ffff8801b74be8e8 R09: 0000000000000000 [ 31.008599] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d99c5b80 [ 31.016055] R13: ffff8801b5516788 R14: 0000000000000000 R15: ffffffff83013be0 [ 31.023330] FS: 0000000000ba5880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 31.031662] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.037530] CR2: 0000000000000080 CR3: 00000001b98a4000 CR4: 00000000001606f0 [ 31.044789] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 31.052063] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 31.059659] Stack: [ 31.062340] ffff8801b5bf7700 ffff8801b5516780 ffff8801b5bf7ad0 ffff8801b5bf79d8 [ 31.070419] ffff8801d95bfce8 ffffffff836c47f2 ffff8801b5bf7b40 ffff8801b5bf7700 [ 31.078599] ffffffff836c4720 ffff8801d95bfd20 ffffffff83021095 ffff8801b5bf7b40 [ 31.086726] Call Trace: [ 31.089326] [] pppol2tp_session_destruct+0xd2/0x110 [ 31.096027] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.102444] [] __sk_destruct+0x55/0x590 [ 31.108093] [] ? sock_release+0x1c0/0x1c0 [ 31.113893] [] sk_destruct+0x63/0x80 [ 31.119295] [] __sk_free+0x4f/0x220 [ 31.124600] [] sk_free+0x2b/0x40 [ 31.129698] [] pppol2tp_release+0x239/0x2e0 [ 31.135736] [] sock_release+0x96/0x1c0 [ 31.142189] [] sock_close+0x16/0x20 [ 31.147488] [] __fput+0x263/0x700 [ 31.153441] [] ____fput+0x15/0x20 [ 31.158617] [] task_work_run+0x10c/0x180 [ 31.164632] [] exit_to_usermode_loop+0xfc/0x120 [ 31.172161] [] do_syscall_64+0x364/0x490 [ 31.177956] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.184925] 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 55 1b ca fd 4c 89 ea 48 b8 00 [ 31.213853] RIP [] l2tp_session_free+0x11c/0x200 [ 31.220756] RSP [ 31.224372] CR2: 0000000000000080 [ 31.228210] ---[ end trace d5673dab5708babc ]--- [ 31.233006] Kernel panic - not syncing: Fatal exception [ 31.239176] Dumping ftrace buffer: [ 31.242760] (ftrace buffer empty) [ 31.246534] Kernel Offset: disabled [ 31.250214] Rebooting in 86400 seconds..