Re: Executing from readablee, no-exec pages

On Thu, 2007-07-05 at 16:55 -0500, Scott Wood wrote:

As revealed by the recent "Prevent data exception in kernel space" 
patch, versions of glibc prior to 2.4[1] assume that, on powerpc32, they 
can execute out of any readable mapping, regardless of whether it is 
marked for execution.  This happens in the elf_machine_load_address() 
function.

Umm, are you sure about this? The "prevent data exception in kernel
space" patch came from a test program I had that attempted to execute a
page with /no permissions/ at all!

I know that I used to have problems with mono making this assumption but
these have since been fixed; however if I understand you correctly then
you can always pre-fault the page by a read and then execute it so I
don't see the point in not doing the change you suggest.

johannes