Fix various bugs found by Coverity Prevent.

--- debugger/dbxface.c	22 Mar 2007 18:02:34 -0000	1.10
+++ debugger/dbxface.c	29 Mar 2007 21:47:10 -0000
@@ -380,7 +380,8 @@
         if ((Op->Common.AmlOpcode == AML_IF_OP) ||
             (Op->Common.AmlOpcode == AML_WHILE_OP))
         {
-            if (WalkState->ControlState->Common.Value)
+            if ((WalkState->ControlState) &&
+                (WalkState->ControlState->Common.Value))
             {
                 AcpiOsPrintf ("Predicate = [True], IF block was executed\n");
             }
--- disassembler/dmwalk.c	22 Mar 2007 17:23:30 -0000	1.1.1.11
+++ disassembler/dmwalk.c	29 Mar 2007 21:47:11 -0000
@@ -1023,7 +1023,7 @@
             AcpiDmIndent (Level - 1);
             AcpiOsPrintf ("{\n");
         }
-        else
+        else if (Op->Common.Parent)
         {
             Op->Common.Parent->Common.DisasmFlags |=
                                     ACPI_PARSEOP_EMPTY_TERMLIST;
--- interpreter/dispatcher/dsmethod.c	22 Mar 2007 17:23:39 -0000	1.1.1.27
+++ interpreter/dispatcher/dsmethod.c	29 Mar 2007 21:47:11 -0000
@@ -682,8 +682,11 @@
         MethodDesc->Method.Mutex->Mutex.AcquisitionDepth--;
         if (!MethodDesc->Method.Mutex->Mutex.AcquisitionDepth)
         {
-            WalkState->Thread->CurrentSyncLevel =
-                MethodDesc->Method.Mutex->Mutex.OriginalSyncLevel;
+            if (WalkState)
+            {
+                WalkState->Thread->CurrentSyncLevel =
+                    MethodDesc->Method.Mutex->Mutex.OriginalSyncLevel;
+            }
 
             AcpiOsReleaseMutex (MethodDesc->Method.Mutex->Mutex.OsMutex);
             MethodDesc->Method.Mutex->Mutex.ThreadId = 0;
--- interpreter/dispatcher/dsopcode.c	22 Mar 2007 17:23:39 -0000	1.1.1.28
+++ interpreter/dispatcher/dsopcode.c	29 Mar 2007 21:47:12 -0000
@@ -298,6 +298,11 @@
     /* Get the AML pointer (method object) and BufferField node */
 
     ExtraDesc = AcpiNsGetSecondaryObject (ObjDesc);
+    if (!ExtraDesc)
+    {
+        return_ACPI_STATUS (AE_NOT_EXIST);
+    }
+
     Node = ObjDesc->BufferField.Node;
 
     ACPI_DEBUG_EXEC(AcpiUtDisplayInitPathname (ACPI_TYPE_BUFFER_FIELD, Node, NULL));
--- interpreter/executer/exmutex.c	22 Mar 2007 17:23:41 -0000	1.1.1.14
+++ interpreter/executer/exmutex.c	29 Mar 2007 21:47:12 -0000
@@ -480,6 +480,15 @@
         return_ACPI_STATUS (AE_AML_MUTEX_NOT_ACQUIRED);
     }
 
+    /* Must have a valid thread ID */
+
+    if (!WalkState->Thread)
+    {
+        ACPI_ERROR ((AE_INFO, "Cannot release Mutex [%4.4s], null thread info",
+            AcpiUtGetNodeName (ObjDesc->Mutex.Node)));
+        return_ACPI_STATUS (AE_AML_INTERNAL);
+    }
+
     /*
      * The Mutex is owned, but this thread must be the owner.
      * Special case for Global Lock, any thread can release
@@ -495,15 +504,6 @@
         return_ACPI_STATUS (AE_AML_NOT_OWNER);
     }
 
-    /* Must have a valid thread ID */
-
-    if (!WalkState->Thread)
-    {
-        ACPI_ERROR ((AE_INFO, "Cannot release Mutex [%4.4s], null thread info",
-            AcpiUtGetNodeName (ObjDesc->Mutex.Node)));
-        return_ACPI_STATUS (AE_AML_INTERNAL);
-    }
-
     /*
      * The sync level of the mutex must be less than or equal to the current
      * sync level
--- interpreter/executer/exoparg3.c	22 Mar 2007 17:23:42 -0000	1.1.1.11
+++ interpreter/executer/exoparg3.c	29 Mar 2007 21:47:12 -0000
@@ -200,7 +200,8 @@
 
         /* Might return while OS is shutting down, just continue */
 
-        ACPI_FREE (Fatal);
+        if (Fatal)
+            ACPI_FREE (Fatal);
         break;
 
 
--- namespace/nsdump.c	22 Mar 2007 17:23:46 -0000	1.1.1.27
+++ namespace/nsdump.c	29 Mar 2007 21:47:12 -0000
@@ -288,6 +288,13 @@
     }
 
     ThisNode = AcpiNsMapHandleToNode (ObjHandle);
+
+    if (!ThisNode)
+    {
+        ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "Null name table entry\n"));
+        return (AE_OK);
+    }
+
     Type = ThisNode->Type;
 
     /* Check if the owner matches */