Andreas Kling f598bbbb1d Kernel: Prevent executing I/O instructions in userspace ... All threads were running with iomapbase=0 in their TSS, which the CPU interprets as "there's an I/O permission bitmap starting at offset 0 into my TSS". Because of that, any bits that were 1 inside the TSS would allow the thread to execute I/O instructions on the port with that bit index. Fix this by always setting the iomapbase to sizeof(TSS32), and also setting the TSS descriptor's limit to sizeof(TSS32), effectively making the I/O permissions bitmap zero-length. This should make it no longer possible to do I/O from userspace. :^)		2020-01-01 17:31:41 +01:00
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man	Kernel: Prevent executing I/O instructions in userspace	2020-01-01 17:31:41 +01:00