Re: [External] [PATCH] platform/x86: think-lmi: Fix reference leak

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Thanks Armin,

On 9/23/23 16:41, 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(). 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")
Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
---
  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


Reviewed-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>

Do you have any reports of our platforms where these are seen? If so I'd like to get it fixed in FW too (and I can get it tested on HW if that helps)

Mark




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