Commit 22ff1a36 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Andy Shevchenko
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platform/x86: alienware-wmi: fix format string overflow warning 

gcc points out a possible format string overflow for a large value of 'zone':

drivers/platform/x86/alienware-wmi.c: In function 'alienware_wmi_init':
drivers/platform/x86/alienware-wmi.c:461:24: error: '%02X' directive writing between 2 and 8 bytes into a region of size 6 [-Werror=format-overflow=]
   sprintf(buffer, "zone%02X", i);
                        ^~~~
drivers/platform/x86/alienware-wmi.c:461:19: note: directive argument in the range [0, 2147483646]
   sprintf(buffer, "zone%02X", i);
                   ^~~~~~~~~~
drivers/platform/x86/alienware-wmi.c:461:3: note: 'sprintf' output between 7 and 13 bytes into a destination of size 10

This replaces the 'int' variable with an 'u8' to make sure
it always fits, renaming the variable to 'zone' for clarity.

Unfortunately, gcc-7.1.1 still warns about it with that change, which
seems to be unintended by the gcc developers. I have opened a bug
against gcc with a reduced test case. As a workaround, I also
change the format string to use "%02hhX", which shuts up the
warning in that version.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81483
Link: https://patchwork.ozlabs.org/patch/788415/


Suggested-by: default avatarAndy Shevchenko <andy@infradead.org>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
[andy: added empty lines after u8 zone; definitions]
Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
parent cd0223c6

drivers/platform/x86/alienware-wmi.c

+21 −19
Original line number Diff line number Diff line
@@ -255,12 +255,13 @@ static int parse_rgb(const char *buf, struct platform_zone *zone) 


static struct platform_zone *match_zone(struct device_attribute *attr)

{

	int i;

	for (i = 0; i < quirks->num_zones; i++) {

		if ((struct device_attribute *)zone_data[i].attr == attr) {

	u8 zone;



	for (zone = 0; zone < quirks->num_zones; zone++) {

		if ((struct device_attribute *)zone_data[zone].attr == attr) {

			pr_debug("alienware-wmi: matched zone location: %d\n",

				 zone_data[i].location);

			return &zone_data[i];

				 zone_data[zone].location);

			return &zone_data[zone];

		}

	}

	return NULL;
@@ -420,7 +421,7 @@ static DEVICE_ATTR(lighting_control_state, 0644, show_control_state, 


static int alienware_zone_init(struct platform_device *dev)

{

	int i;

	u8 zone;

	char buffer[10];

	char *name;
@@ -457,19 +458,19 @@ static int alienware_zone_init(struct platform_device *dev) 
	if (!zone_data)

		return -ENOMEM;



	for (i = 0; i < quirks->num_zones; i++) {

		sprintf(buffer, "zone%02X", i);

	for (zone = 0; zone < quirks->num_zones; zone++) {

		sprintf(buffer, "zone%02hhX", zone);

		name = kstrdup(buffer, GFP_KERNEL);

		if (name == NULL)

			return 1;

		sysfs_attr_init(&zone_dev_attrs[i].attr);

		zone_dev_attrs[i].attr.name = name;

		zone_dev_attrs[i].attr.mode = 0644;

		zone_dev_attrs[i].show = zone_show;

		zone_dev_attrs[i].store = zone_set;

		zone_data[i].location = i;

		zone_attrs[i] = &zone_dev_attrs[i].attr;

		zone_data[i].attr = &zone_dev_attrs[i];

		sysfs_attr_init(&zone_dev_attrs[zone].attr);

		zone_dev_attrs[zone].attr.name = name;

		zone_dev_attrs[zone].attr.mode = 0644;

		zone_dev_attrs[zone].show = zone_show;

		zone_dev_attrs[zone].store = zone_set;

		zone_data[zone].location = zone;

		zone_attrs[zone] = &zone_dev_attrs[zone].attr;

		zone_data[zone].attr = &zone_dev_attrs[zone];

	}

	zone_attrs[quirks->num_zones] = &dev_attr_lighting_control_state.attr;

	zone_attribute_group.attrs = zone_attrs;
@@ -481,12 +482,13 @@ static int alienware_zone_init(struct platform_device *dev) 


static void alienware_zone_exit(struct platform_device *dev)

{

	u8 zone;



	sysfs_remove_group(&dev->dev.kobj, &zone_attribute_group);

	led_classdev_unregister(&global_led);

	if (zone_dev_attrs) {

		int i;

		for (i = 0; i < quirks->num_zones; i++)

			kfree(zone_dev_attrs[i].attr.name);

		for (zone = 0; zone < quirks->num_zones; zone++)

			kfree(zone_dev_attrs[zone].attr.name);

	}

	kfree(zone_dev_attrs);

	kfree(zone_data);