Re: [PATCH v4 2/3] fdt: add support for rng-seed

Nicolas Boichat
2019-05-21T12:42:48Z

On Tue, May 21, 2019 at 12:10 PM Hsin-Yi Wang <hsinyi@chromium.org> wrote:
>
> On Mon, May 20, 2019 at 7:54 AM Nicolas Boichat <drinkcat@chromium.org> wrote:
>
> > Alphabetical order.
> Original headers are not sorted, should I sort them here?
> >
>
> >
> > I'm a little bit concerned about this, as we really want the rng-seed
> > value to be wiped, and not kept in memory (even if it's hard to
> > access).
> >
> > IIUC, fdt_delprop splices the device tree, so it'll override
> > "rng-seed" property with whatever device tree entries follow it.
> > However, if rng-seed is the last property (or if the entries that
> > follow are smaller than rng-seed), the seed will stay in memory (or
> > part of it).
> >
> > fdt_nop_property in v2 would erase it for sure. I don't know if there
> > is a way to make sure that rng-seed is removed for good while still
> > deleting the property (maybe modify fdt_splice_ to do a memset(.., 0)
> > of the moved chunk?).
> >
> So maybe we can use fdt_nop_property() back?

Yes I prefer fdt_nop_property, if we don't want to modify delprop or
splice. But it'd be good if others can chime in.