[PATCH v3 0/2] platform/x86: Fix reference leaks

[PATCH v3 0/2] platform/x86: Fix reference leaks

[Armin Wolf]

If a duplicate attribute is found using kset_find_obj(), a reference
to that attribute is returned which needs to be disposed accordingly
using kobject_put(). This issue likely first appeared inside the
dell-wmi-sysman driver, see
commit 7295a996fdab ("platform/x86: dell-sysman: Fix reference leak").
However, it also seems that the bug was copied from this driver into
the think-lmi and hp-bioscfg drivers. Maybe a more abstract
fw_attr_class could prevent such issues in the future by abstracting
away the kobject handling?

Armin Wolf (2):
  platform/x86: think-lmi: Fix reference leak
  platform/x86: hp-bioscfg: Fix reference leak

 drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 14 ++++++++----
 drivers/platform/x86/think-lmi.c             | 24 ++++++++++++++++----
 2 files changed, 30 insertions(+), 8 deletions(-)

--
2.39.2

[PATCH v3 1/2] platform/x86: think-lmi: Fix reference leak

[Armin Wolf]

If a duplicate attribute is found using kset_find_obj(), a reference
to that attribute is returned which needs to be disposed accordingly
using kobject_put(). Move the setting name validation into a separate
function to allow for this change without having to duplicate the
cleanup code for this setting.
As a side note, a very similar bug was fixed in
commit 7295a996fdab ("platform/x86: dell-sysman: Fix reference leak"),
so it seems that the bug was copied from that driver.

Compile-tested only.

Fixes: 1bcad8e510b2 ("platform/x86: think-lmi: Fix issues with duplicate attributes")
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
Changes in v3:
- add Reviewed-by
Changes in v2:
- no changes
---
 drivers/platform/x86/think-lmi.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
index 4be6f28d4600..3a396b763c49 100644
--- a/drivers/platform/x86/think-lmi.c
+++ b/drivers/platform/x86/think-lmi.c
@@ -1344,6 +1344,24 @@ static void tlmi_release_attr(void)
 	kset_unregister(tlmi_priv.authentication_kset);
 }

+static int tlmi_validate_setting_name(struct kset *attribute_kset, char *name)
+{
+	struct kobject *duplicate;
+
+	if (!strcmp(name, "Reserved"))
+		return -EINVAL;
+
+	duplicate = kset_find_obj(attribute_kset, name);
+	if (duplicate) {
+		pr_debug("Duplicate attribute name found - %s\n", name);
+		/* kset_find_obj() returns a reference */
+		kobject_put(duplicate);
+		return -EBUSY;
+	}
+
+	return 0;
+}
+
 static int tlmi_sysfs_init(void)
 {
 	int i, ret;
@@ -1372,10 +1390,8 @@ static int tlmi_sysfs_init(void)
 			continue;

 		/* check for duplicate or reserved values */
-		if (kset_find_obj(tlmi_priv.attribute_kset, tlmi_priv.setting[i]->display_name) ||
-		    !strcmp(tlmi_priv.setting[i]->display_name, "Reserved")) {
-			pr_debug("duplicate or reserved attribute name found - %s\n",
-				tlmi_priv.setting[i]->display_name);
+		if (tlmi_validate_setting_name(tlmi_priv.attribute_kset,
+					       tlmi_priv.setting[i]->display_name) < 0) {
 			kfree(tlmi_priv.setting[i]->possible_values);
 			kfree(tlmi_priv.setting[i]);
 			tlmi_priv.setting[i] = NULL;
--
2.39.2

[PATCH v3 2/2] platform/x86: hp-bioscfg: Fix reference leak

[Armin Wolf]

If a duplicate attribute is found using kset_find_obj(), a reference
to that attribute is returned which needs to be disposed accordingly
using kobject_put(). Use kobject_put() to dispose the duplicate
attribute in such a case.
As a side note, a very similar bug was fixed in
commit 7295a996fdab ("platform/x86: dell-sysman: Fix reference leak"),
so it seems that the bug was copied from that driver.

Compile-tested only.

Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
Changes in v3:
- no changes
Changes in v2:
- add patch
---
 drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
index 8c4f9e12f018..0c83e66f8d0b 100644
--- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
+++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
@@ -659,7 +659,7 @@ static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
 					  const char *guid, int min_elements,
 					  int instance_id)
 {
-	struct kobject *attr_name_kobj;
+	struct kobject *attr_name_kobj, *duplicate;
 	union acpi_object *elements;
 	struct kset *temp_kset;

@@ -704,8 +704,11 @@ static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
 	}

 	/* All duplicate attributes found are ignored */
-	if (kset_find_obj(temp_kset, str_value)) {
+	duplicate = kset_find_obj(temp_kset, str_value);
+	if (duplicate) {
 		pr_debug("Duplicate attribute name found - %s\n", str_value);
+		/* kset_find_obj() returns a reference */
+		kobject_put(duplicate);
 		goto pack_attr_exit;
 	}

@@ -768,7 +771,7 @@ static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
 					 const char *guid, int min_elements,
 					 int instance_id)
 {
-	struct kobject *attr_name_kobj;
+	struct kobject *attr_name_kobj, *duplicate;
 	struct kset *temp_kset;
 	char str[MAX_BUFF_SIZE];

@@ -794,8 +797,11 @@ static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
 		temp_kset = bioscfg_drv.main_dir_kset;

 	/* All duplicate attributes found are ignored */
-	if (kset_find_obj(temp_kset, str)) {
+	duplicate = kset_find_obj(temp_kset, str);
+	if (duplicate) {
 		pr_debug("Duplicate attribute name found - %s\n", str);
+		/*kset_find_obj() returns a reference */
+		kobject_put(duplicate);
 		goto buff_attr_exit;
 	}

--
2.39.2

Re: [PATCH v3 2/2] platform/x86: hp-bioscfg: Fix reference leak

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2824 bytes --]

On Mon, 25 Sep 2023, Armin Wolf wrote:

> If a duplicate attribute is found using kset_find_obj(), a reference
> to that attribute is returned which needs to be disposed accordingly
> using kobject_put(). Use kobject_put() to dispose the duplicate
> attribute in such a case.
> As a side note, a very similar bug was fixed in
> commit 7295a996fdab ("platform/x86: dell-sysman: Fix reference leak"),
> so it seems that the bug was copied from that driver.
> 
> Compile-tested only.
> 
> Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
> Changes in v3:
> - no changes
> Changes in v2:
> - add patch
> ---
>  drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> index 8c4f9e12f018..0c83e66f8d0b 100644
> --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> @@ -659,7 +659,7 @@ static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
>  					  const char *guid, int min_elements,
>  					  int instance_id)
>  {
> -	struct kobject *attr_name_kobj;
> +	struct kobject *attr_name_kobj, *duplicate;
>  	union acpi_object *elements;
>  	struct kset *temp_kset;
> 
> @@ -704,8 +704,11 @@ static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
>  	}
> 
>  	/* All duplicate attributes found are ignored */
> -	if (kset_find_obj(temp_kset, str_value)) {
> +	duplicate = kset_find_obj(temp_kset, str_value);
> +	if (duplicate) {
>  		pr_debug("Duplicate attribute name found - %s\n", str_value);
> +		/* kset_find_obj() returns a reference */
> +		kobject_put(duplicate);
>  		goto pack_attr_exit;
>  	}
> 
> @@ -768,7 +771,7 @@ static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
>  					 const char *guid, int min_elements,
>  					 int instance_id)
>  {
> -	struct kobject *attr_name_kobj;
> +	struct kobject *attr_name_kobj, *duplicate;
>  	struct kset *temp_kset;
>  	char str[MAX_BUFF_SIZE];
> 
> @@ -794,8 +797,11 @@ static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
>  		temp_kset = bioscfg_drv.main_dir_kset;
> 
>  	/* All duplicate attributes found are ignored */
> -	if (kset_find_obj(temp_kset, str)) {
> +	duplicate = kset_find_obj(temp_kset, str);
> +	if (duplicate) {
>  		pr_debug("Duplicate attribute name found - %s\n", str);
> +		/*kset_find_obj() returns a reference */

Thanks. Whitespace is missing here.

Other than that, 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

> +		kobject_put(duplicate);
>  		goto buff_attr_exit;
>  	}
> 
> --
> 2.39.2
> 

-- 
 i.