[PATCH] D14571: [ELF2] - Implemented PT_GNU_STACK support

[Rui Ueyama via llvm-commits]

On Thu, Nov 12, 2015 at 12:50 AM, George Rimar <grimar at accesssoftek.com>
wrote:

> grimar added a comment.
>
> I would also suggest to think about changing the default logic from "stack
> is always executable by default" to opposite one. At least for some targets.
> I dont think there are many apps that uses executable stacks. But having
> it executable is huge security hole.
> We can implement -z execstack/-z noexecstack to control that for those who
> heeds executable one.
>

I think that's a good suggestion, but that made me think of this: we may
want to force users to specify -z execstack if they really want to make the
stack executable. To me, controlling the stack executable-ness using
.note.GNU-stack section is too subtle and fragile. If you have thousands of
object files, and only one file lacks .note.GNU-stack, the entire program's
stack will be executable. It's unlikely to be an intended behavior, and if
it is actually intended, I believe it is reasonable to tell so to the
linker using the -z flag.

So I guess my point is

 - ignore .note.GNU-stack sections at all,
 - make stack non-executable by default,
 - and implement -z execstack

What do you think?
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