[PATCH] dm: core: ofnode: safely fallback in ofnode_lookup_fdt

[Simon Glass]

Hi Caleb,

On Tue, 12 Nov 2024 at 22:21, Caleb Connolly <caleb.connolly at linaro.org> wrote:
>
> Under some conditions it's possible to hit the null condition here like
> when running with OF_LIVE and using the ofnode API before
> initr_of_live() is called. There is very little null
> checking for this in the FDT framework, so returning null here can
> result in weird null pointer conditions.
>
> Instead let's return the control FDT in the fallback case, this is
> usually what the user was expecting.
>
> Signed-off-by: Caleb Connolly <caleb.connolly at linaro.org>
> ---
>  drivers/core/ofnode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
> index 950895e72a99..7a7f25fc537c 100644
> --- a/drivers/core/ofnode.c
> +++ b/drivers/core/ofnode.c
> @@ -152,9 +152,9 @@ void *ofnode_lookup_fdt(ofnode node)
>                 uint i = OFTREE_TREE_ID(node.of_offset);
>
>                 if (i >= oftree_count) {
>                         log_debug("Invalid tree ID %x\n", i);
> -                       return NULL;
> +                       return (void *)gd->fdt_blob;
>                 }
>
>                 return oftree_list[i];
>         } else {
> --
> 2.47.0
>

Eek I really don't like that, since it will silently return an
unexpected value. I think we should panic. Do you know what code path
gets you here?

More work is needed in livetree to sort of the rough edges, sadly...

Regards,
Simon