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KernelTrap: Linux: x86 No Execute Support

Jun 07, 2004, 08:30 (0 Talkback[s])


"Ingo Molnar announced the availablity of support for AMD's NX, or 'no execute' bit for the x86 architecture. Originally introduced by AMD with their Athlon 64 and Opteron processors and marketed as Enhanced Virus Protection, Ingo notes that support for this new bit was also announced by Intel, Transmeta and VIA. Ingo explains:

"'What does this patch do? The pagetable format of current x86 CPUs does not have an 'execute' bit. This means that even if an application maps a memory area without PROT_EXEC, the CPU will still allow code to be executed in this memory. This property is often abused by exploits when they manage to inject hostile code into this memory, for example via a buffer overflow...'"

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