Received-SPF: pass (google.com: domain of linux-kernel+bounces-190472-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Message-ID: <e32fa7ed-be51-44d5-b849-6649da8a8e27@redhat.com>
Date: Mon, 27 May 2024 13:19:21 +0200
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] platform/x86: dell-smbios: Fix wrong token data in sysfs
To: =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
 Armin Wolf <W_Armin@gmx.de>
Cc: platform-driver-x86@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
References: <20240518234744.144484-1-W_Armin@gmx.de>
 <23e67b5e-8e24-0fa4-42bb-e20cb1596601@linux.intel.com>
Content-Language: en-US
From: Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <23e67b5e-8e24-0fa4-42bb-e20cb1596601@linux.intel.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Hi,

On 5/27/24 12:25 PM, Ilpo Järvinen wrote:
> On Sun, 19 May 2024, Armin Wolf wrote:
> 
>> 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>
>> ---
>>  drivers/platform/x86/dell/dell-smbios-base.c | 127 ++++++++-----------
>>  1 file changed, 50 insertions(+), 77 deletions(-)
>>
>> diff --git a/drivers/platform/x86/dell/dell-smbios-base.c b/drivers/platform/x86/dell/dell-smbios-base.c
>> index e61bfaf8b5c4..bc1bc02820d7 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 +422,24 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy)
>>  	}
>>  }
>>
>> -static int match_attribute(struct device *dev,
>> -			   struct device_attribute *attr)
>> +static ssize_t location_show(struct device *dev, struct device_attribute *attr, char *buf)
>>  {
>> -	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)
> 
> This change is littered with just style fixes which are good but do not 
> belong to this patch, such as here to remove the newline. I think it makes 
> this patch noticeably messier to include those extra style changes so 
> please separate them out of this patch.

I agree with Ilpo's remarks that the style changes should be split out,
either pre or post the patch fixing the actual issue.

After that + addressing Ilpo's other review remarks I can merge this
as a fix for 6.10-rc#

Regards,

Hans


> 
>> -{
>> -	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)
>> +static ssize_t value_show(struct device *dev, struct device_attribute *attr, char *buf)
> 
> Another style fix.
> 
>>  {
>> -	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 = {
>> @@ -473,73 +456,65 @@ 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(struct token_sysfs_data), GFP_KERNEL);
> 
> sizeof(*token_entries)
> 
>> +	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);
>> +	/* We need to store both location and value + terminator */
>> +	token_attrs = kcalloc((2 * da_num_tokens) + 1, sizeof(struct attribute *), GFP_KERNEL);
> 
> sizeof(*token_attrs)
> 
>>  	if (!token_attrs)
>>  		goto out_allocate_attrs;
>>
>>  	for (i = 0, j = 0; i < da_num_tokens; i++) {
>> -		/* skip empty */
>> +		/* Skip empty */
> 
> Style change.
> 
>>  		if (da_tokens[i].tokenID == 0)
>>  			continue;
>> -		/* add location */
>> -		location_name = kasprintf(GFP_KERNEL, "%04x_location",
>> -					  da_tokens[i].tokenID);
>> -		if (location_name == NULL)
>> +
>> +		token_entries[i].token = &da_tokens[i];
>> +
> 
>> +		/* Add location */
>> +		location_name = kasprintf(GFP_KERNEL, "%04x_location", da_tokens[i].tokenID);
>> +		if (!location_name)
> 
> Style change x3.
> 
>>  			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;
>> -		continue;
>> -
>> -loop_fail_create_value:
>> -		kfree(location_name);
>> -		goto out_unwind_strings;
> 
>> +		value_name = kasprintf(GFP_KERNEL, "%04x_value", da_tokens[i].tokenID);
>> +		if (!value_name) {
> 
> Style change x2.
> 
>> +			kfree(location_name);
>> +			goto out_unwind_strings;
>> +		}
>> +
>> +		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;
>>  	}
>>  	smbios_attribute_group.attrs = token_attrs;
>>
>>  	ret = sysfs_create_group(&dev->dev.kobj, &smbios_attribute_group);
>>  	if (ret)
>>  		goto out_unwind_strings;
>> +
> 
> Style change.
> 
>>  	return 0;
>>
>>  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;
>>  }
>> @@ -548,15 +523,13 @@ static void free_group(struct platform_device *pdev)
>>  {
>>  	int i;
>>
>> -	sysfs_remove_group(&pdev->dev.kobj,
>> -				&smbios_attribute_group);
>> +	sysfs_remove_group(&pdev->dev.kobj, &smbios_attribute_group);
> 
> Style change.
> 
>