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

From: Hans de Goede
Date: Mon May 27 2024 - 07:19:46 EST

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In reply to: Ilpo Järvinen: "Re: [PATCH] platform/x86: dell-smbios: Fix wrong token data in sysfs"
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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@xxxxxx>
>> ---
>> 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.
>
>

Next message: Christoph Hellwig: "Re: [PATCH 0/2] Improve dmesg output for swapfile+hibernation"
Previous message: Oscar Salvador: "Re: [RFC PATCH v3 03/16] mm: Provide mm_struct and address to huge_ptep_get()"
In reply to: Ilpo Järvinen: "Re: [PATCH] platform/x86: dell-smbios: Fix wrong token data in sysfs"
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