On Tue, 18 Apr 2000, Steve VanDevender wrote:
> Michael Warfield writes:
[SNIPPED...]
> enough protection to make it worth going into the kernel, and I
> understand the people who argue that it's too much of an ugly kludge to
> implement on the x86. But please, quit trying to claim that a
> non-executable stack provides absolutely no protection.
It's not difficult or kludgie on an x86. However, since the kernel
core was started using a stack which was executable, major changes
would have to be made to provide a non-executable stack without
a scrambled hack. A previous patch I saw was just that.
If you started the kernel from scratch, set up code and data segment
descriptors differently, did the context-switching differently, and
did the paging differently, the kernel would be smaller, less kludgie,
would not have an executable stack.
However, everything would have to be done over including 'C' runtime
libraries. This is probably a project for the next Linus, not the current
one. There is probably a 14-year-old writing one in her bedroom at
this very moment.
Cheers,
Dick Johnson
Penguin : Linux version 2.3.41 on an i686 machine (800.63 BogoMips).
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