[PATCH 6.1 123/217] platform/x86: dell-smbios: Fix wrong token data in sysfs

19 Jun 2024

6.1-stable review patch.  If anyone has any objections, please let me know.
------------------
From: Armin Wolf W_Armin@gmx.de
[ Upstream commit 1981b296f858010eae409548fd297659b2cc570e ]
When reading token data from sysfs on my Inspiron 3505, the token
locations and values are wrong. This happens because match_attribute()
blindly assumes that all entries in da_tokens have an associated
entry in token_attrs.
This however is not true as soon as da_tokens[] contains zeroed
token entries. Those entries are being skipped when initialising
token_attrs, breaking the core assumption of match_attribute().
Fix this by defining an extra struct for each pair of token attributes
and use container_of() to retrieve token information.
Tested on a Dell Inspiron 3050.
Fixes: 33b9ca1e53b4 ("platform/x86: dell-smbios: Add a sysfs interface for SMBIOS tokens")
Signed-off-by: Armin Wolf W_Armin@gmx.de
Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com
Link: https://lore.kernel.org/r/20240528204903.445546-1-W_Armin@gmx.de
Reviewed-by: Hans de Goede hdegoede@redhat.com
Signed-off-by: Hans de Goede hdegoede@redhat.com
Signed-off-by: Sasha Levin sashal@kernel.org
---
 drivers/platform/x86/dell/dell-smbios-base.c | 92 ++++++++------------
 1 file changed, 36 insertions(+), 56 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-smbios-base.c b/drivers/platform/x86/dell/dell-smbios-base.c
index e61bfaf8b5c48..86b95206cb1bd 100644
--- a/drivers/platform/x86/dell/dell-smbios-base.c
+++ b/drivers/platform/x86/dell/dell-smbios-base.c
@@ -11,6 +11,7 @@
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/container_of.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/capability.h>
@@ -25,11 +26,16 @@ static u32 da_supported_commands;
 static int da_num_tokens;
 static struct platform_device *platform_device;
 static struct calling_interface_token *da_tokens;
-static struct device_attribute *token_location_attrs;
-static struct device_attribute *token_value_attrs;
+static struct token_sysfs_data *token_entries;
 static struct attribute **token_attrs;
 static DEFINE_MUTEX(smbios_mutex);
+struct token_sysfs_data {
+	struct device_attribute location_attr;
+	struct device_attribute value_attr;
+	struct calling_interface_token *token;
+};
+
 struct smbios_device {
    struct list_head list;
    struct device *device;
@@ -416,47 +422,26 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy)
    }
 }
-static int match_attribute(struct device *dev,
-			   struct device_attribute *attr)
-{
-	int i;
-
-	for (i = 0; i < da_num_tokens * 2; i++) {
-		if (!token_attrs[i])
-			continue;
-		if (strcmp(token_attrs[i]->name, attr->attr.name) == 0)
-			return i/2;
-	}
-	dev_dbg(dev, "couldn't match: %s\n", attr->attr.name);
-	return -EINVAL;
-}
-
 static ssize_t location_show(struct device *dev,
    		     struct device_attribute *attr, char *buf)
 {
-	int i;
+	struct token_sysfs_data *data = container_of(attr, struct token_sysfs_data, location_attr);
if (!capable(CAP_SYS_ADMIN))
    	return -EPERM;
-	i = match_attribute(dev, attr);
-	if (i > 0)
-		return sysfs_emit(buf, "%08x", da_tokens[i].location);
-	return 0;
+	return sysfs_emit(buf, "%08x", data->token->location);
 }
static ssize_t value_show(struct device *dev,
    		  struct device_attribute *attr, char *buf)
 {
-	int i;
+	struct token_sysfs_data *data = container_of(attr, struct token_sysfs_data, value_attr);
if (!capable(CAP_SYS_ADMIN))
    	return -EPERM;
-	i = match_attribute(dev, attr);
-	if (i > 0)
-		return sysfs_emit(buf, "%08x", da_tokens[i].value);
-	return 0;
+	return sysfs_emit(buf, "%08x", data->token->value);
 }
static struct attribute_group smbios_attribute_group = {
@@ -473,22 +458,15 @@ static int build_tokens_sysfs(struct platform_device *dev)
 {
    char *location_name;
    char *value_name;
-	size_t size;
    int ret;
    int i, j;
-	/* (number of tokens  + 1 for null terminated */
-	size = sizeof(struct device_attribute) * (da_num_tokens + 1);
-	token_location_attrs = kzalloc(size, GFP_KERNEL);
-	if (!token_location_attrs)
+	token_entries = kcalloc(da_num_tokens, sizeof(*token_entries), GFP_KERNEL);
+	if (!token_entries)
    	return -ENOMEM;
-	token_value_attrs = kzalloc(size, GFP_KERNEL);
-	if (!token_value_attrs)
-		goto out_allocate_value;
/* need to store both location and value + terminator*/
-	size = sizeof(struct attribute *) * ((2 * da_num_tokens) + 1);
-	token_attrs = kzalloc(size, GFP_KERNEL);
+	token_attrs = kcalloc((2 * da_num_tokens) + 1, sizeof(*token_attrs), GFP_KERNEL);
    if (!token_attrs)
    	goto out_allocate_attrs;
@@ -496,27 +474,32 @@ static int build_tokens_sysfs(struct platform_device *dev)
    	/* skip empty */
    	if (da_tokens[i].tokenID == 0)
    		continue;
+
+		token_entries[i].token = &da_tokens[i];
+
    	/* add location */
    	location_name = kasprintf(GFP_KERNEL, "%04x_location",
    				  da_tokens[i].tokenID);
    	if (location_name == NULL)
    		goto out_unwind_strings;
-		sysfs_attr_init(&token_location_attrs[i].attr);
-		token_location_attrs[i].attr.name = location_name;
-		token_location_attrs[i].attr.mode = 0444;
-		token_location_attrs[i].show = location_show;
-		token_attrs[j++] = &token_location_attrs[i].attr;
+
+		sysfs_attr_init(&token_entries[i].location_attr.attr);
+		token_entries[i].location_attr.attr.name = location_name;
+		token_entries[i].location_attr.attr.mode = 0444;
+		token_entries[i].location_attr.show = location_show;
+		token_attrs[j++] = &token_entries[i].location_attr.attr;
/* add value */
    	value_name = kasprintf(GFP_KERNEL, "%04x_value",
    			       da_tokens[i].tokenID);
    	if (value_name == NULL)
    		goto loop_fail_create_value;
-		sysfs_attr_init(&token_value_attrs[i].attr);
-		token_value_attrs[i].attr.name = value_name;
-		token_value_attrs[i].attr.mode = 0444;
-		token_value_attrs[i].show = value_show;
-		token_attrs[j++] = &token_value_attrs[i].attr;
+
+		sysfs_attr_init(&token_entries[i].value_attr.attr);
+		token_entries[i].value_attr.attr.name = value_name;
+		token_entries[i].value_attr.attr.mode = 0444;
+		token_entries[i].value_attr.show = value_show;
+		token_attrs[j++] = &token_entries[i].value_attr.attr;
    	continue;
loop_fail_create_value:
@@ -532,14 +515,12 @@ static int build_tokens_sysfs(struct platform_device *dev)
out_unwind_strings:
    while (i--) {
-		kfree(token_location_attrs[i].attr.name);
-		kfree(token_value_attrs[i].attr.name);
+		kfree(token_entries[i].location_attr.attr.name);
+		kfree(token_entries[i].value_attr.attr.name);
    }
    kfree(token_attrs);
 out_allocate_attrs:
-	kfree(token_value_attrs);
-out_allocate_value:
-	kfree(token_location_attrs);
+	kfree(token_entries);
return -ENOMEM;
 }
@@ -551,12 +532,11 @@ static void free_group(struct platform_device *pdev)
    sysfs_remove_group(&pdev->dev.kobj,
    			&smbios_attribute_group);
    for (i = 0; i < da_num_tokens; i++) {
-		kfree(token_location_attrs[i].attr.name);
-		kfree(token_value_attrs[i].attr.name);
+		kfree(token_entries[i].location_attr.attr.name);
+		kfree(token_entries[i].value_attr.attr.name);
    }
    kfree(token_attrs);
-	kfree(token_value_attrs);
-	kfree(token_location_attrs);
+	kfree(token_entries);
 }
static int __init dell_smbios_init(void)
-- 
2.43.0





    

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[PATCH 6.1 123/217] platform/x86: dell-smbios: Fix wrong token data in sysfs