On Tue, Jun 16, 2020 at 01:24:15PM +0200, Peter Zijlstra wrote:
> > +void *module_alloc_prot(unsigned long size, pgprot_t prot)
> > {
> > + unsigned int flags = (pgprot_val(prot) & _PAGE_NX) ?
> > + 0 : VM_FLUSH_RESET_PERMS;
> > void *p;
> >
> > if (PAGE_ALIGN(size) > MODULES_LEN)
> > @@ -75,7 +77,7 @@ void *module_alloc(unsigned long size)
> > p = __vmalloc_node_range(size, MODULE_ALIGN,
> > MODULES_VADDR + get_module_load_offset(),
> > MODULES_END, GFP_KERNEL,
> > - PAGE_KERNEL, 0, NUMA_NO_NODE,
> > + prot, flags, NUMA_NO_NODE,
> > __builtin_return_address(0));
> > if (p && (kasan_module_alloc(p, size) < 0)) {
> > vfree(p);
>
> Hurmm.. Yes it would. It just doesn't feel right though. Can't we
> unconditionally set the flag? At worst it makes free a little bit more
> expensive.
>
> The thing is, I don't think _NX is the only prot that needs restoring.
> Any prot other than the default (RW IIRC) needs restoring.
If that actually is the case I think we should just check for
a non-default permission in __vmalloc_node_range itself and handle it
there, which seems like a nice solution.
