[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.512596] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.608039] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.796511] random: sshd: uninitialized urandom read (32 bytes read) [ 17.993467] random: sshd: uninitialized urandom read (32 bytes read) [ 18.124461] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.61' (ECDSA) to the list of known hosts. [ 23.606805] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.809317] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.817553] IP: [] l2tp_session_free+0x11c/0x200 [ 23.824003] PGD 1b8101067 [ 23.826658] PUD 1c2fc3067 PMD 0 [ 23.830149] [ 23.831800] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.836273] Dumping ftrace buffer: [ 23.839787] (ftrace buffer empty) [ 23.843476] Modules linked in: [ 23.846766] CPU: 0 PID: 3801 Comm: syz-executor074 Not tainted 4.9.113-g9905591 #14 [ 23.854534] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.863861] task: ffff8801b9296000 task.stack: ffff8801b6108000 [ 23.869891] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.878741] RSP: 0018:ffff8801b610fca0 EFLAGS: 00010246 [ 23.884163] RAX: dffffc0000000000 RBX: ffff8801b7067b80 RCX: 0000000000000000 [ 23.891407] RDX: 1ffff10036c71dc0 RSI: ffffffff836bcee1 RDI: ffff8801b638ee00 [ 23.898655] RBP: ffff8801b610fcc0 R08: ffff8801b92968e8 R09: 0000000000000000 [ 23.905913] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b638ec80 [ 23.913156] R13: ffff8801b7067b88 R14: 0000000000000000 R15: ffffffff83013be0 [ 23.920402] FS: 00000000026aa880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.928601] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.934454] CR2: 0000000000000080 CR3: 00000001bb6de000 CR4: 00000000001606f0 [ 23.941701] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.948954] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.956204] Stack: [ 23.958330] ffff8801b6ba9980 ffff8801b7067b80 ffff8801b6ba9d50 ffff8801b6ba9c58 [ 23.966319] ffff8801b610fce8 ffffffff836c47f2 ffff8801b6ba9dc0 ffff8801b6ba9980 [ 23.974331] ffffffff836c4720 ffff8801b610fd20 ffffffff83021095 ffff8801b6ba9dc0 [ 23.982341] Call Trace: [ 23.984928] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.991568] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.997858] [] __sk_destruct+0x55/0x590 [ 24.003461] [] ? sock_release+0x1c0/0x1c0 [ 24.009230] [] sk_destruct+0x63/0x80 [ 24.014566] [] __sk_free+0x4f/0x220 [ 24.019817] [] sk_free+0x2b/0x40 [ 24.024809] [] pppol2tp_release+0x239/0x2e0 [ 24.030754] [] sock_release+0x96/0x1c0 [ 24.036266] [] sock_close+0x16/0x20 [ 24.041530] [] __fput+0x263/0x700 [ 24.046607] [] ____fput+0x15/0x20 [ 24.051684] [] task_work_run+0x10c/0x180 [ 24.057370] [] exit_to_usermode_loop+0xfc/0x120 [ 24.063661] [] do_syscall_64+0x364/0x490 [ 24.069347] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.076250] 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 [ 24.103113] RIP [] l2tp_session_free+0x11c/0x200 [ 24.109628] RSP [ 24.113229] CR2: 0000000000000080 [ 24.117380] ---[ end trace 7d2fda834a63d155 ]--- [ 24.122160] Kernel panic - not syncing: Fatal exception [ 24.127940] Dumping ftrace buffer: [ 24.131460] (ftrace buffer empty) [ 24.135143] Kernel Offset: disabled [ 24.138743] Rebooting in 86400 seconds..