Re: Executing from readablee, no-exec pages

On Fri, 2007-07-06 at 10:42 -0400, David Woodhouse wrote:

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

quoted

To maintain compatibility with these versions, we could change the test 
in do_page_fault() to include VM_READ as well as VM_EXEC on targets that 
don't have a separate exec-bit in hardware (are there any powerpc mmus 
that do?).  

64-bit implementations since POWER4 have separate exec permissions,
don't they? So any userspace which tries to execute non-executable pages
is already broken when running on a ppc64 machine; I wouldn't worry too
much about letting it break on ppc32 too.

We already use vDSO signal trampolines even on the 32-bit kernel, right?

The problem was with old glibc 32 bits which used to jump to an
instruction in the .got iirc that wasn't in an executable section

Ben.