mmap RW then mprotect RWX

[Emmanuel Dreyfus]

Hello

I try to fix unoconv, which currently requires paxctl +m ${PYTHONBIN}
to work. The problem is in allocExec() from
 libreoffice/bridges/source/cpp_uno/shared/vtablefactory.cxx

It attempts a mmap() with RW protection, and immediatly a mprotect()
with RWX protection. That chokes with PaX mprotect.

A simple fix seems to just call mmap() with RWX protection and forget
the mprotect(). A simple C program (see below) shows that it works well 
with NetBSD-10.0/amd64 and PaX mprotect enabled. 

I wonder if there are other environments (other NetBSD setups, perhaps?)
where mmap() RW then mprotect() RWX would be required. 

#include <stdio.h>
#include <err.h>
#include <sys/mman.h>

int
main(void)
{
        void *p;

        p = mmap(NULL, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON, -1, 0);
        if (p == NULL)
                err(1, "mmap RWX failed");

        return 0;
}


-- 
Emmanuel Dreyfus
m...@netbsd.org