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serenity/Base/usr
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
..
include Toolchain: Useit.sh finish and added an install target for the libc's Makefile and a bit of ground work for a gcc port 2019-04-29 13:12:20 +02:00
lib Toolchain: Useit.sh finish and added an install target for the libc's Makefile and a bit of ground work for a gcc port 2019-04-29 13:12:20 +02:00
share/man Kernel: Prevent executing I/O instructions in userspace 2020-01-01 17:31:41 +01:00