struct kobject *dirret;
static int foo;

static ssize_t foo_show(struct kobject *kobj, struct kobj_attribute *attr,
		char *buf)
{
	return sprintf(buf, "%d\n", foo);
}

ssize_t foo_store(struct kobject *kobj, struct kobj_attribute *attr,
		const char *buf, size_t count)
{
	sscanf(buf, "%du", &foo);
	return count;
}

struct kobj_attribute foo_attribute = __ATTR(foo, 0660, foo_show, foo_store);

static struct attribute * attrs[] =
{
		&foo_attribute.attr,
		NULL,
};

static struct attribute_group attr_group = {
		.attrs = attrs,
};

struct semaphore Semaphore;

int init_task(void)
{
	printk(KERN_INFO "Task module init.\n");

	dirret = kobject_create_and_add("eudyptula", NULL);

	printk(KERN_INFO "eudyptula dir pointer: %i\n", (int)dirret);

	filevalue = sysfs_create_group(dirret, &attr_group);
	if(filevalue){
		kobject_put(dirret);
		return filevalue;
	}

	sema_init(&Semaphore, 1);

	/* 
	 * A non 0 return means init_module failed; module can't be loaded. 
	 */
	return 0;
}
module_init(init_task);

[   72.377242] task: loading out-of-tree module taints kernel.
[   72.377311] task: module verification failed: signature and/or required key missing - tainting kernel
[   72.379915] Task module init.
[   72.379928] eudyptula dir pointer: 1817486104
[   72.379931] BUG: unable to handle kernel NULL pointer dereference at           (null)
[   72.379939] IP: init_module+0x51/0x148 [task]
[   72.379941] PGD 0 
[   72.379941] P4D 0 

[   72.379945] Oops: 0002 [#1] SMP
[   72.379947] Modules linked in: task(OE+) rfcomm vmw_vsock_vmci_transport vsock bnep vmw_balloon snd_ens1371 snd_ac97_codec ac97_bus gameport snd_pcm coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc snd_seq_midi aesni_intel aes_x86_64 crypto_simd glue_helper cryptd snd_seq_midi_event intel_rapl_perf snd_rawmidi input_leds snd_seq joydev serio_raw uvcvideo videobuf2_vmalloc snd_seq_device videobuf2_memops snd_timer btusb videobuf2_v4l2 videobuf2_core btrtl videodev btbcm btintel bluetooth snd media soundcore ecdh_generic vmw_vmci i2c_piix4 shpchp nfit mac_hid parport_pc ppdev lp parport autofs4 vmw_pvscsi vmxnet3 vmwgfx hid_generic ttm drm_kms_helper syscopyarea sysfillrect sysimgblt psmouse fb_sys_fops drm ahci usbhid e1000 hid mptspi libahci mptscsih mptbase scsi_transport_spi pata_acpi
[   72.379989] CPU: 1 PID: 2880 Comm: insmod Tainted: G    B      OE   4.12.0-rc2+ #3
[   72.379991] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015
[   72.379993] task: ffff9fabf8253280 task.stack: ffffafc1449b8000
[   72.379996] RIP: 0010:init_module+0x51/0x148 [task]
[   72.379997] RSP: 0018:ffffafc1449bbc88 EFLAGS: 00010282
[   72.379998] RAX: 0000000000000000 RBX: ffffffffc0209080 RCX: 0000000000000006
[   72.379999] RDX: 00000000000001b6 RSI: ffffffffc0209000 RDI: ffff9fac8164df40
[   72.380000] RBP: ffffafc1449bbc90 R08: 0000000000000001 R09: 00000000000007d9
[   72.380001] R10: ffff9fac6c54a318 R11: 00000000000007d9 R12: ffffffffc0207060
[   72.380002] R13: 0000000000000000 R14: ffff9fabe6d1fb18 R15: 0000000000000001
[   72.380003] FS:  00007fd2a5809700(0000) GS:ffff9fac81640000(0000) knlGS:0000000000000000
[   72.380004] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   72.380005] CR2: 0000000000000000 CR3: 0000000104dc9000 CR4: 00000000001406e0
[   72.380049] Call Trace:
[   72.380056]  do_one_initcall+0x53/0x190
[   72.380060]  ? kmem_cache_alloc_trace+0x18f/0x1e0
[   72.380062]  ? kfree+0x18e/0x1a0
[   72.380067]  do_init_module+0x5f/0x20d
[   72.380071]  load_module+0x282d/0x2c10
[   72.380074]  ? ima_post_read_file+0x7d/0xa0
[   72.380078]  ? security_kernel_post_read_file+0x6b/0x80
[   72.380081]  SYSC_finit_module+0xdf/0x110
[   72.380084]  ? SYSC_finit_module+0xdf/0x110
[   72.380087]  SyS_finit_module+0xe/0x10
[   72.380091]  entry_SYSCALL_64_fastpath+0x1e/0xa9
[   72.380092] RIP: 0033:0x7fd2a5338499
[   72.380094] RSP: 002b:00007ffc28371f38 EFLAGS: 00000202 ORIG_RAX: 0000000000000139
[   72.380096] RAX: ffffffffffffffda RBX: 00007fd2a55fbb20 RCX: 00007fd2a5338499
[   72.380098] RDX: 0000000000000000 RSI: 000055a6b2723246 RDI: 0000000000000003
[   72.380100] RBP: 0000000000001011 R08: 0000000000000000 R09: 00007fd2a55fdea0
[   72.380101] R10: 0000000000000003 R11: 0000000000000202 R12: 00007fd2a55fbb78
[   72.380102] R13: 00007fd2a55fbb78 R14: 000000000000270f R15: 00007fd2a55fc1a8
[   72.380104] Code: c4 e3 d8 48 c7 c7 4b 80 20 c0 89 c6 48 89 05 37 24 00 00 e8 f1 88 ba d8 48 8b 05 23 24 00 00 ba b6 01 00 00 48 c7 c6 00 90 20 c0 <48> c7 00 68 80 20 c0 48 8b 05 09 24 00 00 48 8b 3d 0a 24 00 00 
[   72.380126] RIP: init_module+0x51/0x148 [task] RSP: ffffafc1449bbc88
[   72.380127] CR2: 0000000000000000
[   72.380128] ---[ end trace a7920e8cfd6a71df ]---