Commit ec851b23 authored by Zeng Heng's avatar Zeng Heng Committed by Bartosz Golaszewski
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gpiolib: fix memory leak in gpiochip_setup_dev() 



Here is a backtrace report about memory leak detected in
gpiochip_setup_dev():

unreferenced object 0xffff88810b406400 (size 512):
  comm "python3", pid 1682, jiffies 4295346908 (age 24.090s)
  backtrace:
    kmalloc_trace
    device_add		device_private_init at drivers/base/core.c:3361
			(inlined by) device_add at drivers/base/core.c:3411
    cdev_device_add
    gpiolib_cdev_register
    gpiochip_setup_dev
    gpiochip_add_data_with_key

gcdev_register() & gcdev_unregister() would call device_add() &
device_del() (no matter CONFIG_GPIO_CDEV is enabled or not) to
register/unregister device.

However, if device_add() succeeds, some resource (like
struct device_private allocated by device_private_init())
is not released by device_del().

Therefore, after device_add() succeeds by gcdev_register(), it
needs to call put_device() to release resource in the error handle
path.

Here we move forward the register of release function, and let it
release every piece of resource by put_device() instead of kfree().

While at it, fix another subtle issue, i.e. when gc->ngpio is equal
to 0, we still call kcalloc() and, in case of further error, kfree()
on the ZERO_PTR pointer, which is not NULL. It's not a bug per se,
but rather waste of the resources and potentially wrong expectation
about contents of the gdev->descs variable.

Fixes: 159f3cd9 ("gpiolib: Defer gpio device setup until after gpiolib initialization")
Signed-off-by: default avatarZeng Heng <zengheng4@huawei.com>
Co-developed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
parent b7b275e6

drivers/gpio/gpiolib.c

+26 −16
Original line number Diff line number Diff line
@@ -526,12 +526,13 @@ static int gpiochip_setup_dev(struct gpio_device *gdev) 
	if (ret)

		return ret;



	/* From this point, the .release() function cleans up gpio_device */

	gdev->dev.release = gpiodevice_release;



	ret = gpiochip_sysfs_register(gdev);

	if (ret)

		goto err_remove_device;



	/* From this point, the .release() function cleans up gpio_device */

	gdev->dev.release = gpiodevice_release;

	dev_dbg(&gdev->dev, "registered GPIOs %d to %d on %s\n", gdev->base,

		gdev->base + gdev->ngpio - 1, gdev->chip->label ? : "generic");
@@ -597,10 +598,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, 
	struct fwnode_handle *fwnode = NULL;

	struct gpio_device *gdev;

	unsigned long flags;

	int base = gc->base;

	unsigned int i;

	u32 ngpios = 0;

	int base = 0;

	int ret = 0;

	u32 ngpios;



	if (gc->fwnode)

		fwnode = gc->fwnode;
@@ -647,17 +648,12 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, 
	else

		gdev->owner = THIS_MODULE;



	gdev->descs = kcalloc(gc->ngpio, sizeof(gdev->descs[0]), GFP_KERNEL);

	if (!gdev->descs) {

		ret = -ENOMEM;

		goto err_free_dev_name;

	}



	/*

	 * Try the device properties if the driver didn't supply the number

	 * of GPIO lines.

	 */

	if (gc->ngpio == 0) {

	ngpios = gc->ngpio;

	if (ngpios == 0) {

		ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);

		if (ret == -ENODATA)

			/*
@@ -668,7 +664,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, 
			 */

			ngpios = 0;

		else if (ret)

			goto err_free_descs;

			goto err_free_dev_name;



		gc->ngpio = ngpios;

	}
@@ -676,13 +672,19 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, 
	if (gc->ngpio == 0) {

		chip_err(gc, "tried to insert a GPIO chip with zero lines\n");

		ret = -EINVAL;

		goto err_free_descs;

		goto err_free_dev_name;

	}



	if (gc->ngpio > FASTPATH_NGPIO)

		chip_warn(gc, "line cnt %u is greater than fast path cnt %u\n",

			  gc->ngpio, FASTPATH_NGPIO);



	gdev->descs = kcalloc(gc->ngpio, sizeof(*gdev->descs), GFP_KERNEL);

	if (!gdev->descs) {

		ret = -ENOMEM;

		goto err_free_dev_name;

	}



	gdev->label = kstrdup_const(gc->label ?: "unknown", GFP_KERNEL);

	if (!gdev->label) {

		ret = -ENOMEM;
@@ -701,11 +703,13 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, 
	 * it may be a pipe dream. It will not happen before we get rid

	 * of the sysfs interface anyways.

	 */

	base = gc->base;

	if (base < 0) {

		base = gpiochip_find_base(gc->ngpio);

		if (base < 0) {

			ret = base;

			spin_unlock_irqrestore(&gpio_lock, flags);

			ret = base;

			base = 0;

			goto err_free_label;

		}

		/*
@@ -816,6 +820,11 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, 
err_free_gpiochip_mask:

	gpiochip_remove_pin_ranges(gc);

	gpiochip_free_valid_mask(gc);

	if (gdev->dev.release) {

		/* release() has been registered by gpiochip_setup_dev() */

		put_device(&gdev->dev);

		goto err_print_message;

	}

err_remove_from_list:

	spin_lock_irqsave(&gpio_lock, flags);

	list_del(&gdev->list);
@@ -829,13 +838,14 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, 
err_free_ida:

	ida_free(&gpio_ida, gdev->id);

err_free_gdev:

	kfree(gdev);

err_print_message:

	/* failures here can mean systems won't boot... */

	if (ret != -EPROBE_DEFER) {

		pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n", __func__,

		       gdev->base, gdev->base + gdev->ngpio - 1,

		       base, base + (int)ngpios - 1,

		       gc->label ? : "generic", ret);

	}

	kfree(gdev);

	return ret;

}

EXPORT_SYMBOL_GPL(gpiochip_add_data_with_key);