Re: [PATCH] libfdt: fix fdt_check_node_offset_ w/ VALID_INPUT

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Thu, Aug 13, 2020 at 09:55:09AM +0200, Frank Mehnert wrote:
> fdt_check_node_offset_() checks for a valid offset but also changes the
> offset by calling fdt_next_tag(). Hence, do not skip this function if
> ASSUME_VALID_INPUT is set.
> 
> Actually this works similar to fdt_check_prop_offset_().

Correct, but we can do better.  We can still elide the checks for
offset < 0 and offset % FDT_TAGSIZE when VALID_INPUT is set.

> ---
>  libfdt/fdt.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/libfdt/fdt.c b/libfdt/fdt.c
> index c28fcc1..39ed8ed 100644
> --- a/libfdt/fdt.c
> +++ b/libfdt/fdt.c
> @@ -206,8 +206,6 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
> 
>  int fdt_check_node_offset_(const void *fdt, int offset)
>  {
> -       if (can_assume(VALID_INPUT))
> -               return offset;
>         if ((offset < 0) || (offset % FDT_TAGSIZE)
>             || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
>                 return -FDT_ERR_BADOFFSET;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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