[PATCH] acpi: Incorrect ACPI tables walk in acpi_tables_sysfs_init

[PATCH] acpi: Incorrect ACPI tables walk in acpi_tables_sysfs_init

[Jeremy Compostella]

Date: Thu, 21 Nov 2013 11:20:23 +0100
Message-ID: <87d2lu83a0.fsf@tldlab276.tl.intel.com>
MIME-Version: 1.0
Content-Type: text/plain
--text follows this line--
Hi,

When executing on a ACPI Hardware reduced hardware, all the ACPI tables are not
exposed in sysfs due to the fact that FACS is silently ignored by the kernel in
ACPI hardware reduced and, moreover, the acpi_tables_sysfs_init ACPI table walk
is buggy and stop too soon.

The acpi_tables_sysfs_init function should to rely on the appropriate
acpi_status return values to decide or not to stop the iteration.  This way,
when running on a ACPI Reduced Harware environment where the FACS table is
silently ignored by the kernel or some ACPI table are not correctly memory
mapped or have a bad checksum it would not stop the iteration.

Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>

---
 drivers/acpi/sysfs.c |   52 ++++++++++++++++++++++++++------------------------
 1 file changed, 27 insertions(+), 25 deletions(-)

diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index fcae5fa..72a3250 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -354,8 +354,9 @@ static int acpi_tables_sysfs_init(void)
 {
 	struct acpi_table_attr *table_attr;
 	struct acpi_table_header *table_header = NULL;
-	int table_index = 0;
-	int result;
+	int table_index;
+	acpi_status status;
+	int ret;
 
 	tables_kobj = kobject_create_and_add("tables", acpi_kobj);
 	if (!tables_kobj)
@@ -365,33 +366,34 @@ static int acpi_tables_sysfs_init(void)
 	if (!dynamic_tables_kobj)
 		goto err_dynamic_tables;
 
-	do {
-		result = acpi_get_table_by_index(table_index, &table_header);
-		if (!result) {
-			table_index++;
-			table_attr = NULL;
-			table_attr =
-			    kzalloc(sizeof(struct acpi_table_attr), GFP_KERNEL);
-			if (!table_attr)
-				return -ENOMEM;
-
-			acpi_table_attr_init(table_attr, table_header);
-			result =
-			    sysfs_create_bin_file(tables_kobj,
-						  &table_attr->attr);
-			if (result) {
-				kfree(table_attr);
-				return result;
-			} else
-				list_add_tail(&table_attr->node,
-					      &acpi_table_attr_list);
+	for (table_index = 0;; table_index++) {
+		status = acpi_get_table_by_index(table_index, &table_header);
+
+		if (status == AE_BAD_PARAMETER)
+			break;
+
+		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);
+		if (ret) {
+			kfree(table_attr);
+			return ret;
 		}
-	} while (!result);
+		list_add_tail(&table_attr->node, &acpi_table_attr_list);
+	}
+
 	kobject_uevent(tables_kobj, KOBJ_ADD);
 	kobject_uevent(dynamic_tables_kobj, KOBJ_ADD);
-	result = acpi_install_table_handler(acpi_sysfs_table_handler, NULL);
+	status = acpi_install_table_handler(acpi_sysfs_table_handler, NULL);
 
-	return result == AE_OK ? 0 : -EINVAL;
+	return ACPI_FAILURE(status) ? -EINVAL : 0;
 err_dynamic_tables:
 	kobject_put(tables_kobj);
 err:
-- 
1.7.10.4

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Re: [PATCH] acpi: Incorrect ACPI tables walk in acpi_tables_sysfs_init

[Rafael J. Wysocki]

On Thursday, November 21, 2013 11:20:27 AM Jeremy Compostella wrote:
> Date: Thu, 21 Nov 2013 11:20:23 +0100
> Message-ID: <87d2lu83a0.fsf@tldlab276.tl.intel.com>
> MIME-Version: 1.0
> Content-Type: text/plain
> --text follows this line--
> Hi,
> 
> When executing on a ACPI Hardware reduced hardware, all the ACPI tables are not
> exposed in sysfs due to the fact that FACS is silently ignored by the kernel in
> ACPI hardware reduced and, moreover, the acpi_tables_sysfs_init ACPI table walk
> is buggy and stop too soon.
> 
> The acpi_tables_sysfs_init function should to rely on the appropriate
> acpi_status return values to decide or not to stop the iteration.  This way,
> when running on a ACPI Reduced Harware environment where the FACS table is
> silently ignored by the kernel or some ACPI table are not correctly memory
> mapped or have a bad checksum it would not stop the iteration.
> 
> Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>

Since this is a fix, I've modified the subject and changelog slightly and
queued up the patch for the next ACPI pull request (next week).

Thanks!

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.