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• #88 Erasmus őstag

  2004-02-25 12:01:37 #88

  Összes hozzászólása itt Válaszok az összes hozzászólására itt Válaszok erre a hozzászólásra

  Privát üzenet küldése

  

  Erasmus

  őstag

  Megjelent a Windows XP SP2 leírása: [L]http://www.microsoft.com/downloads/details.aspx?FamilyID=7bd948d7-b791-40b6-8364-685b84158c78&DisplayLang=en[/L]
  
  Ebben részletesen írnak az execution protectionről (NX). Egy részlet a bevezetésből:
  
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  Execution protection (also known as NX, or no execute) marks all memory locations in a process as non-executable unless the location explicitly contains executable code. There is a class of attacks that attempt to insert and execute code from non-executable memory locations. Execution protection mitigates this by intercepting these attempts and raising an exception.
  
  Execution protection relies on processor hardware to mark memory with an attribute that indicates that code should not be executed from that memory. Execution protection functions on a per-virtual memory page basis, most often changing a bit in the page table entry (PTE) to mark the memory page.
  The actual hardware implementation of execution protection and marking of the virtual memory page varies by processor architecture. However, processors that support execution protection are capable of raising an exception when code is executed from a page marked with the appropriate attribute set.
  
  Both Intel and Advanced Micro Devices (AMD) have defined and shipped Windows-compatible architectures for execution protection. Windows supports execution protection on the AMD64 platform and Intel Itanium Processor Family (IPF) processors.
  
  The 32-bit version of Windows (beginning with Service Pack 2 for Windows XP) utilizes the no-execute page-protection (NX) processor feature as defined by AMD. In order to use the NX processor feature, the processor must be running in Physical Address Extension (PAE) mode. The 64-bit versions of Windows uses the NX processor feature on 64-bit extensions processors and certain values of the access rights page table entry (PTE) field on IPF processors.
  
  It is hoped that future 32-bit and 64-bit processors will provide execution protection. Microsoft is addressing possible compatibility issues with existing applications and drivers while working with processor vendors to encourage the adoption and development of execution protection technologies.
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  Ezek szerint a Prescottban mégsincs NX-támogatás, ahogy azt korábban sejteni lehetett.
  
  Valaki le tudná írni, hogy pontosan hogyan is müx majd a dolog?
  
  kösz,

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