Commit 4feba70a authored by Peter Gruber's avatar Peter Gruber Committed by Len Brown
Browse files

ACPI: avoid empty file name in sysfs 

Since commit bc45b1d3 acpi tables are
allowed to have an empty signature and /sys/firmware/acpi/tables uses the
signature as filename.  Applications using naive recursion through /sys
loop forever.  A possible solution would be: (replacing the zero length
filename with the string "NULL")

http://bugzilla.kernel.org/show_bug.cgi?id=11539



Acked-by: default avatarZhang Rui <rui.zhang@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 49fdf678

drivers/acpi/system.c

+17 −8
Original line number Diff line number Diff line
@@ -78,9 +78,15 @@ static ssize_t acpi_table_show(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(table_attr->name, table_attr->instance,

	    acpi_get_table(name, table_attr->instance,

			   &table_header);

	if (ACPI_FAILURE(status))

		return -ENODEV;
@@ -95,21 +101,24 @@ static void acpi_table_attr_init(struct acpi_table_attr *table_attr, 
	struct acpi_table_header *header = NULL;

	struct acpi_table_attr *attr = NULL;



	memcpy(table_attr->name, table_header->signature, ACPI_NAME_SIZE);

	if (table_header->signature[0] != '\0')

		memcpy(table_attr->name, table_header->signature,

			ACPI_NAME_SIZE);

	else

		memcpy(table_attr->name, "NULL", 4);



	list_for_each_entry(attr, &acpi_table_attr_list, node) {

		if (!memcmp(table_header->signature, attr->name,

			    ACPI_NAME_SIZE))

		if (!memcmp(table_attr->name, attr->name, ACPI_NAME_SIZE))

			if (table_attr->instance < attr->instance)

				table_attr->instance = attr->instance;

	}

	table_attr->instance++;



	if (table_attr->instance > 1 || (table_attr->instance == 1 &&

					 !acpi_get_table(table_header->

							 signature, 2,

							 &header)))

		sprintf(table_attr->name + 4, "%d", table_attr->instance);

					!acpi_get_table

					(table_header->signature, 2, &header)))

		sprintf(table_attr->name + ACPI_NAME_SIZE, "%d",

			table_attr->instance);



	table_attr->attr.size = 0;

	table_attr->attr.read = acpi_table_show;

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