ACPI / sysfs: Update sysfs signature handling code

This patch cleans up sysfs table signature handling code:

 1. Convert the signature handling code to use the ACPICA APIs to
    benefit from the future improvements of the APIs.

 2. Add 'filename' attribute in order to handle both BE/LE name tags.

 3. Add instance check in order to avoid the possible buffer overflow
    related to the table file name.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index c88d4bd..703c26e 100644 (file)
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -314,10 +314,14 @@ static struct kobject *tables_kobj;
 static struct kobject *dynamic_tables_kobj;
 static struct kobject *hotplug_kobj;
 
+#define ACPI_MAX_TABLE_INSTANCES       999
+#define ACPI_INST_SIZE                 4 /* including trailing 0 */
+
 struct acpi_table_attr {
        struct bin_attribute attr;
-       char name[8];
+       char name[ACPI_NAME_SIZE];
        int instance;
+       char filename[ACPI_NAME_SIZE+ACPI_INST_SIZE];
        struct list_head node;
 };
 
@@ -329,14 +333,9 @@ static ssize_t acpi_table_show(struct file *filp, struct kobject *kobj,
            container_of(bin_attr, struct acpi_table_attr, attr);
        struct acpi_table_header *table_header = NULL;
        acpi_status status;
-       char name[ACPI_NAME_SIZE];
 
-       if (strncmp(table_attr->name, "NULL", 4))
-               memcpy(name, table_attr->name, ACPI_NAME_SIZE);
-       else
-               memcpy(name, "\0\0\0\0", 4);
-
-       status = acpi_get_table(name, table_attr->instance, &table_header);
+       status = acpi_get_table(table_attr->name, table_attr->instance,
+                               &table_header);
        if (ACPI_FAILURE(status))
                return -ENODEV;
 
@@ -344,38 +343,45 @@ static ssize_t acpi_table_show(struct file *filp, struct kobject *kobj,
                                       table_header, table_header->length);
 }
 
-static void acpi_table_attr_init(struct acpi_table_attr *table_attr,
-                                struct acpi_table_header *table_header)
+static int acpi_table_attr_init(struct kobject *tables_obj,
+                               struct acpi_table_attr *table_attr,
+                               struct acpi_table_header *table_header)
 {
        struct acpi_table_header *header = NULL;
        struct acpi_table_attr *attr = NULL;
+       char instance_str[ACPI_INST_SIZE];
 
        sysfs_attr_init(&table_attr->attr.attr);
-       if (table_header->signature[0] != '\0')
-               memcpy(table_attr->name, table_header->signature,
-                      ACPI_NAME_SIZE);
-       else
-               memcpy(table_attr->name, "NULL", 4);
+       ACPI_MOVE_NAME(table_attr->name, table_header->signature);
 
        list_for_each_entry(attr, &acpi_table_attr_list, node) {
-               if (!memcmp(table_attr->name, attr->name, ACPI_NAME_SIZE))
+               if (ACPI_COMPARE_NAME(table_attr->name, attr->name))
                        if (table_attr->instance < attr->instance)
                                table_attr->instance = attr->instance;
        }
        table_attr->instance++;
+       if (table_attr->instance > ACPI_MAX_TABLE_INSTANCES) {
+               pr_warn("%4.4s: too many table instances\n",
+                       table_attr->name);
+               return -ERANGE;
+       }
 
+       ACPI_MOVE_NAME(table_attr->filename, table_header->signature);
+       table_attr->filename[ACPI_NAME_SIZE] = '\0';
        if (table_attr->instance > 1 || (table_attr->instance == 1 &&
                                         !acpi_get_table
-                                        (table_header->signature, 2, &header)))
-               sprintf(table_attr->name + ACPI_NAME_SIZE, "%d",
-                       table_attr->instance);
+                                        (table_header->signature, 2, &header))) {
+               snprintf(instance_str, sizeof(instance_str), "%u",
+                        table_attr->instance);
+               strcat(table_attr->filename, instance_str);
+       }
 
        table_attr->attr.size = table_header->length;
        table_attr->attr.read = acpi_table_show;
-       table_attr->attr.attr.name = table_attr->name;
+       table_attr->attr.attr.name = table_attr->filename;
        table_attr->attr.attr.mode = 0400;
 
-       return;
+       return sysfs_create_bin_file(tables_obj, &table_attr->attr);
 }
 
 acpi_status acpi_sysfs_table_handler(u32 event, void *table, void *context)
@@ -389,13 +395,12 @@ acpi_status acpi_sysfs_table_handler(u32 event, void *table, void *context)
                if (!table_attr)
                        return AE_NO_MEMORY;
 
-               acpi_table_attr_init(table_attr, table);
-               if (sysfs_create_bin_file(dynamic_tables_kobj,
-                                         &table_attr->attr)) {
+               if (acpi_table_attr_init(dynamic_tables_kobj,
+                                        table_attr, table)) {
                        kfree(table_attr);
                        return AE_ERROR;
-               } else
-                       list_add_tail(&table_attr->node, &acpi_table_attr_list);
+               }
+               list_add_tail(&table_attr->node, &acpi_table_attr_list);
                break;
        case ACPI_TABLE_EVENT_LOAD:
        case ACPI_TABLE_EVENT_UNLOAD:
@@ -437,13 +442,12 @@ static int acpi_tables_sysfs_init(void)
                if (ACPI_FAILURE(status))
                        continue;
 
-               table_attr = NULL;
                table_attr = kzalloc(sizeof(*table_attr), GFP_KERNEL);
                if (!table_attr)
                        return -ENOMEM;
 
-               acpi_table_attr_init(table_attr, table_header);
-               ret = sysfs_create_bin_file(tables_kobj, &table_attr->attr);
+               ret = acpi_table_attr_init(tables_kobj,
+                                          table_attr, table_header);
                if (ret) {
                        kfree(table_attr);
                        return ret;