Re: [rft, PATCH v5 1/1] gpiolib: fix memory leak in gpiochip_setup_dev()
From: Zeng Heng
Date: Sat Nov 19 2022 - 05:15:56 EST
On 2022/11/19 3:45, Andy Shevchenko wrote:
From: Zeng Heng <zengheng4@xxxxxxxxxx>
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: 159f3cd92f17 ("gpiolib: Defer gpio device setup until after gpiolib initialization")
Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx>
Co-developed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
changes in v5 (done by Andy):
- refactored to avoid double checks on the same conditionals
- moved kcalloc() after validating its parameter
- compiled tested only by me (Andy)
I have applied the patch on local environment, and it works fine after
rough test
(which is based on QEMU simulated).
Best regards,
Zeng Heng
changes in v4:
- add gpiochip_print_register_fail()
changes in v3:
- use put_device() instead of kfree() explicitly
changes in v2:
- correct fixes tag
drivers/gpio/gpiolib.c | 42 ++++++++++++++++++++++++++----------------
1 file changed, 26 insertions(+), 16 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index caa747fdcb72..119c9c3a2a50 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -580,12 +580,13 @@ 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");
@@ -651,10 +652,10 @@ 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 the calling driver did not initialize firmware node, do it here */
if (gc->fwnode)
@@ -696,17 +697,12 @@ 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)
/*
@@ -717,7 +713,7 @@ 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;
}
@@ -725,13 +721,19 @@ 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;
@@ -750,11 +752,13 @@ 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;
}
/*
@@ -868,6 +872,11 @@ 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);
@@ -881,13 +890,14 @@ 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);