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gpio: mockup: Convert to use software nodes

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The gpio-mockup driver creates the properties that are shared between
platform and GPIO devices. Because of that, the properties may not
be removed at the proper point of time without provoking a use-after-free
as shown in the following backtrace:

  refcount_t: underflow; use-after-free.
  WARNING: CPU: 0 PID: 103 at lib/refcount.c:28 refcount_warn_saturate+0xd1/0x120
  ...
  Call Trace:
  kobject_put+0xdc/0xf0
  software_node_notify_remove+0xa8/0xc0
  device_del+0x15a/0x3e0

That's why the driver has to manage the lifetime of the software nodes
by itself.

The problem originates from the old device_add_properties() API, but
has been only revealed after the commit bd1e336aa8 ("driver core: platform:
Remove platform_device_add_properties()"). Hence, it's used as a landmark
for backporting.

Fixes: bd1e336aa8 ("driver core: platform: Remove platform_device_add_properties()")
Reported-by: Kent Gibson <warthog618@gmail.com>
Tested-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[Bartosz: tweaked local variable placement]
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
This commit is contained in:
Andy Shevchenko 2021-10-05 15:24:49 +03:00 committed by Bartosz Golaszewski
parent 55a9968c7e
commit 6fda593f30
1 changed files with 18 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/gpio/gpio-mockup.c
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@ -476,10 +476,19 @@ static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
static void gpio_mockup_unregister_pdevs(void)
{
struct platform_device *pdev;
struct fwnode_handle *fwnode;
int i;
for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++)
platform_device_unregister(gpio_mockup_pdevs[i]);
for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
pdev = gpio_mockup_pdevs[i];
if (!pdev)
continue;
fwnode = dev_fwnode(&pdev->dev);
platform_device_unregister(pdev);
fwnode_remove_software_node(fwnode);
}
}
static __init char **gpio_mockup_make_line_names(const char *label,
@ -508,6 +517,7 @@ static int __init gpio_mockup_register_chip(int idx)
struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
struct platform_device_info pdevinfo;
struct platform_device *pdev;
struct fwnode_handle *fwnode;
char **line_names = NULL;
char chip_label[32];
int prop = 0, base;
@ -536,13 +546,18 @@ static int __init gpio_mockup_register_chip(int idx)
"gpio-line-names", line_names, ngpio);
}
fwnode = fwnode_create_software_node(properties, NULL);
if (IS_ERR(fwnode))
return PTR_ERR(fwnode);
pdevinfo.name = "gpio-mockup";
pdevinfo.id = idx;
pdevinfo.properties = properties;
pdevinfo.fwnode = fwnode;
pdev = platform_device_register_full(&pdevinfo);
kfree_strarray(line_names, ngpio);
if (IS_ERR(pdev)) {
fwnode_remove_software_node(fwnode);
pr_err("error registering device");
return PTR_ERR(pdev);
}