[tkreuzer] 55173: [FREELDR] Fix wrong buffer size calculation that could lead to memory corruption Kudos go to Jardar for debugging the issue.

Author: tkreuzer
Date: Wed Jan 25 16:45:42 2012
New Revision: 55173

URL: http://svn.reactos.org/svn/reactos?rev=55173&view=rev
Log:
[FREELDR]
Fix wrong buffer size calculation that could lead to memory corruption
Kudos go to Jardar for debugging the issue.

Modified:
    trunk/reactos/boot/freeldr/freeldr/arch/i386/hardware.c

Modified: trunk/reactos/boot/freeldr/freeldr/arch/i386/hardware.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/boot/freeldr/freeldr/arch/i...
==============================================================================
--- trunk/reactos/boot/freeldr/freeldr/arch/i386/hardware.c [iso-8859-1] (original)
+++ trunk/reactos/boot/freeldr/freeldr/arch/i386/hardware.c [iso-8859-1] Wed Jan 25 16:45:42 2012
@@ -250,7 +250,8 @@
   TRACE("Estimated buffer size %u\n", NodeSize * NodeCount);

/* Set 'Configuration Data' value */
-  Size = sizeof(CM_PARTIAL_RESOURCE_LIST) + (NodeSize * NodeCount);
+  Size = sizeof(CM_PARTIAL_RESOURCE_LIST)
+        + sizeof(CM_PNP_BIOS_INSTALLATION_CHECK) + (NodeSize * NodeCount);
   PartialResourceList = MmHeapAlloc(Size);
   if (PartialResourceList == NULL)
     {
@@ -268,8 +269,8 @@
   PartialResourceList->PartialDescriptors[0].ShareDisposition =
     CmResourceShareUndetermined;

-  Ptr = (char *)(((ULONG_PTR)&PartialResourceList->PartialDescriptors[0]) +
-		 sizeof(CM_PARTIAL_RESOURCE_DESCRIPTOR));
+  /* The buffer starts after PartialResourceList->PartialDescriptors[0] */
+  Ptr = (char *)(PartialResourceList + 1);

/* Set instalation check data */
   memcpy (Ptr, InstData, sizeof(CM_PNP_BIOS_INSTALLATION_CHECK));
@@ -291,6 +292,12 @@
    	    DeviceNode->Node,
    	    DeviceNode->Size,
    	    DeviceNode->Size);
+
+      if (PnpBufferSize + DeviceNode->Size > Size)
+      {
+          ERR("Buffer too small!\n");
+          break;
+      }

memcpy (Ptr,
    	  DeviceNode,