[Gcl-devel] Re: gcl-2.6.1 on Fedora Core?

[Camm Maguire]

The following message is a courtesy copy of an article
that has been posted to comp.lang.lisp as well.

Greetings, and thanks!  We already add -Wa,--execstack to the cflags,
but this is not enough.  (I'm assuming that is equivalent to the ld
flag -- could be wrong here.)  With gcl and emacs, the problem is not
with an executable stack -- gcl never executes code off its stack.
Its just that principally speaking, unexec assumes that sbrk expanded
.data sections are contiguous -- it can't unexec an image with a hole
between where the ld-produced .data section ended and where the first
sbrk() started.  It does not appear that --execstack turns off brk
randomization.  But setarch does.  Would greatly appreciate
clarification/enlightenment/some internal marking to achieve this goal
as apart from an executable stack.

Take care,

David Golden <address@hidden> writes:

> Camm Maguire wrote:
> 
> 
> > 
> > If there is a way in which a program can internally, i.e. from within,
> > do its own 'setarch' and one can explain this to me, I'd be happy to
> > put it in GCL, configured in when appropriate. 
> 
> I think you need to make sure the ELF binary object that is loaded
> has an annotation section telling the kernel and ld.so that it needs
> executable stack - google for PT_GNU_STACK.
> 
> According to the link below (near the end of the linked document), the
> linker (GNU ld) included with Fedora accepts "-z execstack" to signal that
> this section should be included and indicate executable stack.
> 
> http://fedora.redhat.com/docs/release-notes/
> 
> 
> 
> 
> 
> 
> 
> 

-- 
Camm Maguire                                            address@hidden
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