[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.818335] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.543556] random: sshd: uninitialized urandom read (32 bytes read) [ 21.962663] random: sshd: uninitialized urandom read (32 bytes read) [ 22.685792] random: sshd: uninitialized urandom read (32 bytes read) [ 22.810087] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.10' (ECDSA) to the list of known hosts. [ 28.210949] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.443945] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.452261] IP: [] l2tp_session_free+0x11c/0x200 [ 28.458695] PGD 1bcf52067 [ 28.461359] PUD 1bcecb067 PMD 0 [ 28.464858] [ 28.466508] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.470983] Dumping ftrace buffer: [ 28.474504] (ftrace buffer empty) [ 28.478220] Modules linked in: [ 28.481535] CPU: 0 PID: 3803 Comm: syz-executor980 Not tainted 4.9.116-g52be322 #69 [ 28.489317] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.498656] task: ffff8801c3d28000 task.stack: ffff8801da3a8000 [ 28.504710] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.513592] RSP: 0018:ffff8801da3afca0 EFLAGS: 00010246 [ 28.519033] RAX: dffffc0000000000 RBX: ffff8801b54c8000 RCX: 0000000000000000 [ 28.526287] RDX: 1ffff10039432080 RSI: ffffffff836be8f1 RDI: ffff8801ca190400 [ 28.533535] RBP: ffff8801da3afcc0 R08: ffff8801c3d288e8 R09: 0000000000000000 [ 28.540794] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca190280 [ 28.548046] R13: ffff8801b54c8008 R14: 0000000000000000 R15: ffffffff83014be0 [ 28.555306] FS: 0000000001b23880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 28.563511] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.569371] CR2: 0000000000000080 CR3: 00000001b6e5e000 CR4: 00000000001606f0 [ 28.576636] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.583932] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.591200] Stack: [ 28.593341] ffff8801c6bba200 ffff8801b54c8000 ffff8801c6bba5d0 ffff8801c6bba4d8 [ 28.601390] ffff8801da3afce8 ffffffff836c6202 ffff8801c6bba640 ffff8801c6bba200 [ 28.609413] ffffffff836c6130 ffff8801da3afd20 ffffffff83022095 ffff8801c6bba640 [ 28.617434] Call Trace: [ 28.620006] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.626660] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.632981] [] __sk_destruct+0x55/0x590 [ 28.638585] [] ? sock_release+0x1c0/0x1c0 [ 28.644370] [] sk_destruct+0x63/0x80 [ 28.649721] [] __sk_free+0x4f/0x220 [ 28.654985] [] sk_free+0x2b/0x40 [ 28.659992] [] pppol2tp_release+0x239/0x2e0 [ 28.665942] [] sock_release+0x96/0x1c0 [ 28.671485] [] sock_close+0x16/0x20 [ 28.676751] [] __fput+0x263/0x700 [ 28.681829] [] ____fput+0x15/0x20 [ 28.686911] [] task_work_run+0x10c/0x180 [ 28.692610] [] exit_to_usermode_loop+0xfc/0x120 [ 28.698907] [] do_syscall_64+0x364/0x490 [ 28.704689] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.711591] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 28.738938] RIP [] l2tp_session_free+0x11c/0x200 [ 28.745452] RSP [ 28.749056] CR2: 0000000000000080 [ 28.752866] ---[ end trace d59134fa147eb987 ]--- [ 28.757658] Kernel panic - not syncing: Fatal exception [ 28.763555] Dumping ftrace buffer: [ 28.767081] (ftrace buffer empty) [ 28.770770] Kernel Offset: disabled [ 28.774374] Rebooting in 86400 seconds..