http://bugzilla.kernel.org/show_bug.cgi?id=11539
Summary: empty filename in /sys/firmware/acpi/tables
Product: ACPI
Version: 2.5
KernelVersion: 2.6.26
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: Other
AssignedTo: [EMAIL PROTECTED]
ReportedBy: [EMAIL PROTECTED]
Hardware Environment:
A system with an acpi table with an empty signature
Problem Description:
Since commit bc45b1d39a925b56796bebf8a397a0491489d85c 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")
diff a/drivers/acpi/system.c b/drivers/acpi/system.c
--- a/drivers/acpi/system.c
+++ b/drivers/acpi/system.c
@@ -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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