[sir_richard] 49439: [NTOS]: Fix a bug in MmFindGapBottomUp which could make it return an address lower than what the caller said should be the lowest address.

Author: sir_richard
Date: Tue Nov  2 14:50:06 2010
New Revision: 49439
URL: http://svn.reactos.org/svn/reactos?rev=49439&view=rev
Log:
[NTOS]: Fix a bug in MmFindGapBottomUp which could make it return an address lower than
what the caller said should be the lowest address.
Modified:
    trunk/reactos/ntoskrnl/mm/marea.c
Modified: trunk/reactos/ntoskrnl/mm/marea.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/mm/marea.c?rev=49…
==============================================================================
--- trunk/reactos/ntoskrnl/mm/marea.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/mm/marea.c [iso-8859-1] Tue Nov  2 14:50:06 2010
@@ -492,13 +492,16 @@
          break;
       AlignedAddress = MM_ROUND_UP(PreviousNode->EndingAddress, Granularity);
-      if (Node->StartingAddress > AlignedAddress &&
-          (ULONG_PTR)Node->StartingAddress - (ULONG_PTR)AlignedAddress >= Length)
-      {
-         DPRINT("MmFindGapBottomUp: %p\n", AlignedAddress);
-         return AlignedAddress;
-      }
-
+      if (AlignedAddress >= LowestAddress)
+      {
+          if (Node->StartingAddress > AlignedAddress &&
+              (ULONG_PTR)Node->StartingAddress - (ULONG_PTR)AlignedAddress >=
Length)
+          {
+             DPRINT("MmFindGapBottomUp: %p\n", AlignedAddress);
+             ASSERT(AlignedAddress >= LowestAddress);
+             return AlignedAddress;
+          }
+      }
       PreviousNode = Node;
    }
@@ -508,6 +511,7 @@
        (ULONG_PTR)HighestAddress - (ULONG_PTR)AlignedAddress >= Length)
    {
       DPRINT("MmFindGapBottomUp: %p\n", AlignedAddress);
+      ASSERT(AlignedAddress >= LowestAddress);
       return AlignedAddress;
    }
@@ -517,6 +521,7 @@
        (ULONG_PTR)FirstNode->StartingAddress - (ULONG_PTR)AlignedAddress >= Length)
    {
       DPRINT("MmFindGapBottomUp: %p\n", AlignedAddress);
+      ASSERT(AlignedAddress >= LowestAddress);
       return AlignedAddress;
    }