Bug 585 – Incorrect zero-length Buffer to String conversion

Bug 585 - Incorrect zero-length Buffer to String conversion

Summary:

Incorrect zero-length Buffer to String conversion

Status:	RESOLVED FIXED

Product:	ACPICA
Component:	Core/Interpreter
Version:	unspecified
Platform:	All Linux

Importance:	P3 normal
Assigned To:	Bob Moore

URL:
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2007-02-03 05:28 by Fiodor Suietov
Modified:	2008-09-26 19:55 (History)

Attachments
ASL code to reproduce the bug (1.31 KB, text/plain) 2007-02-03 05:29, Fiodor Suietov	Details
Add an attachment (proposed patch, testcase, etc.)

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Description From Fiodor Suietov 2007-02-03 05:28:55

Neither ToDecimalString and ToHexString reference nor the Buffer to
String conversion rule (Table 17-8 Object Conversion Rules) describes
the result of their use for a zero-length Buffer. Apparently a zero
length string looks like a natural result there.

The attached demo shows that a zero-length Buffer to String conversion
is implemented incorrectly now (the results of conversion differ from
a zero length string).


INTERNAL BUG NUMBER:

   293

------- Comment #1 From Fiodor Suietov 2007-02-03 05:29:44 -------

Created an attachment (id=630) [details]
ASL code to reproduce the bug

------- Comment #2 From Fiodor Suietov 2007-02-03 05:38:58 -------

Possible fix:

+++ exconvrt.c	2007-01-31 15:25:46.573712500 +0300
@@ -638,7 +638,11 @@ AcpiExConvertToString (
          * Create a new string object and string buffer
          * (-1 because of extra separator included in StringLength from above)
          */
-        ReturnDesc = AcpiUtCreateStringObject ((ACPI_SIZE) (StringLength - 
1));
+        if (StringLength)
+        {
+            StringLength--;
+        }
+        ReturnDesc = AcpiUtCreateStringObject ((ACPI_SIZE) StringLength);
         if (!ReturnDesc)
         {
             return_ACPI_STATUS (AE_NO_MEMORY);
@@ -662,7 +666,9 @@ AcpiExConvertToString (
          * Null terminate the string
          * (overwrites final comma/space from above)
          */
-        NewBuf--;
+        if (ObjDesc->Buffer.Length) {
+            NewBuf--;
+        }
         *NewBuf = 0;
         break;

------- Comment #3 From Lin Ming 2007-12-04 13:30:37 -------

Windows doesn't support converting zero-length Buffer

------- Comment #4 From Lin Ming 2008-09-26 19:55:55 -------

ship in ACPICA release 20080926