Re: [PATCH v7 13/14] module: Do not set nx for module memory before freeing

[Andy Lutomirski]

On Wed, Dec 5, 2018 at 12:52 AM Nadav Amit <namit@xxxxxxxxxx> wrote:
>
> When module memory is about to be freed, there is no apparent reason to
> make it (and its data) executable, but that's exactly what is done
> today. This is not efficient and not secure.
>
> There are various theories why it was done, but none of them seem as
> something that really require it today. nios2 uses kmalloc for module
> memory, but anyhow it does not change the PTEs of the module memory.  In
> x86, changing vmalloc'd memory mappings also modifies the direct mapping
> alias, but the NX-bit is not modified in such way.
>
> So let's remove it. Andy suggested that the changes of the PTEs can be
> avoided (excluding the direct-mapping alias), which is true. However,
> in x86 it requires some cleanup of the contiguous page allocator, which
> is outside of the scope of this patch-set.
>


I'm okay with this, but I'd like to see Rick's stuff get rebased on
top of it and clean it up for real.