[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.191136] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.276967] random: sshd: uninitialized urandom read (32 bytes read) [ 17.566338] random: sshd: uninitialized urandom read (32 bytes read) [ 18.523535] random: sshd: uninitialized urandom read (32 bytes read) [ 18.655269] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.56' (ECDSA) to the list of known hosts. [ 24.066165] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.272982] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.281201] IP: [] l2tp_session_free+0x11c/0x200 [ 24.287626] PGD 1b7437067 [ 24.290265] PUD 1b7be8067 PMD 0 [ 24.293738] [ 24.295356] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.299826] Dumping ftrace buffer: [ 24.303344] (ftrace buffer empty) [ 24.307025] Modules linked in: [ 24.310317] CPU: 0 PID: 3799 Comm: syz-executor366 Not tainted 4.9.113-g9905591 #66 [ 24.318086] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.327412] task: ffff8801b74db000 task.stack: ffff8801d8cd0000 [ 24.333437] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.342282] RSP: 0018:ffff8801d8cd7ca0 EFLAGS: 00010246 [ 24.347703] RAX: dffffc0000000000 RBX: ffff8801c6fabb80 RCX: 0000000000000000 [ 24.354948] RDX: 1ffff10036f3f880 RSI: ffffffff836bcee1 RDI: ffff8801b79fc400 [ 24.362210] RBP: ffff8801d8cd7cc0 R08: ffff8801b74db8e8 R09: 0000000000000000 [ 24.369807] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b79fc280 [ 24.377050] R13: ffff8801c6fabb88 R14: 0000000000000000 R15: ffffffff83013be0 [ 24.384296] FS: 0000000000e9c880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.392495] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.398356] CR2: 0000000000000080 CR3: 00000001b7436000 CR4: 00000000001606f0 [ 24.405603] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.412857] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.420106] Stack: [ 24.422230] ffff8801da3b5d80 ffff8801c6fabb80 ffff8801da3b6150 ffff8801da3b6058 [ 24.430221] ffff8801d8cd7ce8 ffffffff836c47f2 ffff8801da3b61c0 ffff8801da3b5d80 [ 24.438230] ffffffff836c4720 ffff8801d8cd7d20 ffffffff83021095 ffff8801da3b61c0 [ 24.446206] Call Trace: [ 24.448775] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.455413] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.461705] [] __sk_destruct+0x55/0x590 [ 24.467303] [] ? sock_release+0x1c0/0x1c0 [ 24.473071] [] sk_destruct+0x63/0x80 [ 24.478405] [] __sk_free+0x4f/0x220 [ 24.483655] [] sk_free+0x2b/0x40 [ 24.488645] [] pppol2tp_release+0x239/0x2e0 [ 24.494588] [] sock_release+0x96/0x1c0 [ 24.500097] [] sock_close+0x16/0x20 [ 24.505346] [] __fput+0x263/0x700 [ 24.510426] [] ____fput+0x15/0x20 [ 24.515510] [] task_work_run+0x10c/0x180 [ 24.521193] [] exit_to_usermode_loop+0xfc/0x120 [ 24.527484] [] do_syscall_64+0x364/0x490 [ 24.533169] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.540065] 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 [ 24.566879] RIP [] l2tp_session_free+0x11c/0x200 [ 24.573391] RSP [ 24.576989] CR2: 0000000000000080 [ 24.580709] ---[ end trace a21d3a440659d46b ]--- [ 24.585465] Kernel panic - not syncing: Fatal exception [ 24.591246] Dumping ftrace buffer: [ 24.594769] (ftrace buffer empty) [ 24.598451] Kernel Offset: disabled [ 24.602046] Rebooting in 86400 seconds..