[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.625914] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.894333] random: sshd: uninitialized urandom read (32 bytes read) [ 27.460630] random: sshd: uninitialized urandom read (32 bytes read) [ 27.868681] random: sshd: uninitialized urandom read (32 bytes read) [ 28.000829] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.47' (ECDSA) to the list of known hosts. [ 33.718034] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.921016] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.929233] IP: [] l2tp_session_free+0x11c/0x200 [ 33.935649] PGD 1c0162067 [ 33.938288] PUD 1c0159067 PMD 0 [ 33.941765] [ 33.943389] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.947880] Dumping ftrace buffer: [ 33.951438] (ftrace buffer empty) [ 33.955130] Modules linked in: [ 33.958416] CPU: 0 PID: 3802 Comm: syz-executor703 Not tainted 4.9.122-g54068d6 #26 [ 33.966189] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.975524] task: ffff8801b8214800 task.stack: ffff8801c9d48000 [ 33.981741] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 33.990604] RSP: 0018:ffff8801c9d4fca0 EFLAGS: 00010246 [ 33.996695] RAX: dffffc0000000000 RBX: ffff8801b663f680 RCX: 0000000000000000 [ 34.003949] RDX: 1ffff1003956d480 RSI: ffffffff836c39a1 RDI: ffff8801cab6a400 [ 34.011197] RBP: ffff8801c9d4fcc0 R08: ffff8801b82150e8 R09: 0000000000000000 [ 34.018446] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cab6a280 [ 34.025690] R13: ffff8801b663f688 R14: 0000000000000000 R15: ffffffff83019be0 [ 34.032937] FS: 00000000011fe880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.041197] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.047061] CR2: 0000000000000080 CR3: 00000001b630b000 CR4: 00000000001606f0 [ 34.054367] Stack: [ 34.056498] ffff8801d9841980 ffff8801b663f680 ffff8801d9841d50 ffff8801d9841c58 [ 34.064493] ffff8801c9d4fce8 ffffffff836cb2b2 ffff8801d9841dc0 ffff8801d9841980 [ 34.072545] ffffffff836cb1e0 ffff8801c9d4fd20 ffffffff830270f5 ffff8801d9841dc0 [ 34.080524] Call Trace: [ 34.083102] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.089743] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.096042] [] __sk_destruct+0x55/0x590 [ 34.101645] [] ? sock_release+0x1c0/0x1c0 [ 34.107425] [] sk_destruct+0x63/0x80 [ 34.112811] [] __sk_free+0x4f/0x220 [ 34.118068] [] sk_free+0x2b/0x40 [ 34.123058] [] pppol2tp_release+0x239/0x2e0 [ 34.129002] [] sock_release+0x96/0x1c0 [ 34.134511] [] sock_close+0x16/0x20 [ 34.139829] [] __fput+0x263/0x700 [ 34.144921] [] ____fput+0x15/0x20 [ 34.150007] [] task_work_run+0x10c/0x180 [ 34.155698] [] exit_to_usermode_loop+0xfc/0x120 [ 34.161997] [] do_syscall_64+0x364/0x490 [ 34.167690] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.174588] 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 [ 34.201911] RIP [] l2tp_session_free+0x11c/0x200 [ 34.208424] RSP [ 34.212018] CR2: 0000000000000080 [ 34.215588] ---[ end trace eb8961bb2e6100ff ]--- [ 34.220342] Kernel panic - not syncing: Fatal exception [ 34.225944] Dumping ftrace buffer: [ 34.229462] (ftrace buffer empty) [ 34.233149] Kernel Offset: disabled [ 34.236750] Rebooting in 86400 seconds..