From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Sun, 3 May 2015 03:37:06 +0000 (+0000)
Subject: [FAST486]
X-Git-Tag: backups/colins-printing-for-freedom@73041~89
X-Git-Url: https://git.reactos.org/?p=reactos.git;a=commitdiff_plain;h=923efbbc4e541d6db15ff0d2edd6f6f1420acbf7;hp=3da5321a16cd70c456a130d4fd65bf6b23ce6e96

[FAST486]
Properly check the limit for "expand down" segments.


svn path=/trunk/; revision=67528
---

diff --git a/reactos/lib/fast486/common.c b/reactos/lib/fast486/common.c
index 4f39e6a62ce..4f78e01dbc1 100644
--- a/reactos/lib/fast486/common.c
+++ b/reactos/lib/fast486/common.c
@@ -47,11 +47,23 @@ Fast486ReadMemory(PFAST486_STATE State,
     /* Get the cached descriptor */
     CachedDescriptor = &State->SegmentRegs[SegmentReg];
 
-    if ((Offset + Size - 1) > CachedDescriptor->Limit)
+    if (InstFetch || !CachedDescriptor->DirConf)
     {
-        /* Read beyond limit */
-        Fast486Exception(State, FAST486_EXCEPTION_GP);
-        return FALSE;
+        if ((Offset + Size - 1) > CachedDescriptor->Limit)
+        {
+            /* Read beyond limit */
+            Fast486Exception(State, FAST486_EXCEPTION_GP);
+            return FALSE;
+        }
+    }
+    else
+    {
+        if (Offset < CachedDescriptor->Limit)
+        {
+            /* Read beyond limit */
+            Fast486Exception(State, FAST486_EXCEPTION_GP);
+            return FALSE;
+        }
     }
 
     /* Check for protected mode */
@@ -157,11 +169,23 @@ Fast486WriteMemory(PFAST486_STATE State,
     /* Get the cached descriptor */
     CachedDescriptor = &State->SegmentRegs[SegmentReg];
 
-    if ((Offset + Size - 1) > CachedDescriptor->Limit)
+    if (!CachedDescriptor->DirConf)
     {
-        /* Write beyond limit */
-        Fast486Exception(State, FAST486_EXCEPTION_GP);
-        return FALSE;
+        if ((Offset + Size - 1) > CachedDescriptor->Limit)
+        {
+            /* Write beyond limit */
+            Fast486Exception(State, FAST486_EXCEPTION_GP);
+            return FALSE;
+        }
+    }
+    else
+    {
+        if (Offset < CachedDescriptor->Limit)
+        {
+            /* Read beyond limit */
+            Fast486Exception(State, FAST486_EXCEPTION_GP);
+            return FALSE;
+        }
     }
 
     /* Check for protected mode */