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Re: Fix hppa/ia64/microblaze executable stack default (bug 22156)


On Fri, 22 Sep 2017, John David Anglin wrote:

> > Can someone with hppa-linux hardware confirm what stack permissions the 
> > kernel in fact starts processes with in the absence of GNU-stack markers 
> > (Andreas's analysis indicates non-executable), what if any changes glibc 
> > makes to those permissions after process creation, and whether trampolines 
> > work in such a process?  Testing whether my glibc patch changes the 
> > answers to any of those questions would be a bonus.
> 
> 
> This is what I see for /bin/bash when we reach main:
> f8d01000-f8d23000 rwxp 00000000 00:00 0                                  [stack]
> 
> This what I see for ld.so at _start:
> f8d01000-f8d23000 rwxp 00000000 00:00 0                                  [stack]
> 
> Don't see any GNU-stack markers in either.
> 
> I'll try to test patch this weekend.

Thanks.

Given what Andreas said at 
<https://gcc.gnu.org/ml/gcc-patches/2017-09/msg01220.html>, does this mean 
there are other causes of executable stacks in the kernel, such as 
VM_STACK_DEFAULT_FLAGS?  If so, maybe hppa and microblaze do in fact need 
the GCC patch rather than the glibc one?

-- 
Joseph S. Myers
joseph@codesourcery.com


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