Re: Non-Exec stack patches

From: David Mosberger
Date: Wed Mar 24 2004 - 02:11:13 EST

>>>>> On Tue, 23 Mar 2004 18:01:14 -0800, Ulrich Drepper <drepper@xxxxxxxxxx> said:

Uli> David Mosberger wrote:
>> What stack protections other than RW- and RWX are useful?

Uli> It's not about "what protections". The three currently
Uli> recognized states are PT_GNU_STACK not present, rwx, rw-.
Uli> Ingo's code documents this. For those who need more, I'll have
Uli> a paper coming up for a conference in Toronto in April.

I'd find the PT_GNU_STACK approach much more appealing if it actually
was used to get rid of the stack-special case in the kernel
altogether. Certainly it seems like it could be used to get rid of
STACK_TOP (just use the segment's p_vaddr). That would still leave
the TASK_UNMAPPED_BASE special-case, but at least it would be a step
in the right direction. Also, in the case of ia64, p_memsz could be
used to give user-level control over whether they want the
register/memory stacks to grow towards each other or apart from each

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