New: empty filename in /sys/firmware/acpi/tables

Quoted 20 lines · On Thu, 11 Sep 2008 02:59:49 -0700 (PDT) [email protected] wrote:

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

Quoted 7 lines

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")

drivers/acpi/system.c

Quoted 3 lines

diff a/drivers/acpi/system.c b/drivers/acpi/system.c

drivers/acpi/system.c +0 -0

(argh)

Please don't submit patches via bugzilla, especially not copy-n-paste ones. It gets wordwrapped and tabs get replaced with spaces and similar crap. Patches should be submitted via email.

I cleaned this patch up and applied it locally.

Please send a Signed-off-by: for this patch as per Documentation/SubmittingPatches, section 12.

This patch fixes what appears to be a regression in 2.6.26 and looks like it is applicable to both 2.6.26.x and to 2.6.27. Len, Bob: please review asap - I can merge it with your ack if you'd like.

From: Peter Gruber <[email protected]>

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

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")

Cc Bob Moore <[email protected]>

Cc Lin Ming <[email protected]>

Cc Len Brown <[email protected]>

Cc <[email protected]> [2.6.26.x]

Signed-off-by Andrew Morton <[email protected]>

---

 drivers/acpi/system.c |   25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff -puN drivers/acpi/system.c~acpi-dont-create-empty-filenames-in-sys-firmware-acpi-tables drivers/acpi/system.c

drivers/acpi/system.c renamed from drivers/acpi/system.c~acpi-dont-create-empty-filenames-in-sys-firmware-acpi-tables +17 -8

@@ -78,9 +78,15 @@ static ssize_t acpi_table_show(struct ko
 	    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 
 	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;

_

--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html