On Mon, Sep 21, 2020 at 05:52:50PM +0100, Andre Przywara wrote:
> With -Wsign-compare, compilers warn about mismatching signedness in
> comparisons in fdt_offset_ptr().
>
> This mostly stems from "offset" being passed in as a signed integer,
> even though the function would not really tolerate negative values.
>
> Short of changing the prototype, check that offset is not negative, and
> use an unsigned type internally.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Applied, thanks.
> ---
> libfdt/fdt.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/libfdt/fdt.c b/libfdt/fdt.c
> index 37b7b93..04e1e06 100644
> --- a/libfdt/fdt.c
> +++ b/libfdt/fdt.c
> @@ -134,16 +134,20 @@ int fdt_check_header(const void *fdt)
>
> const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
> {
> - unsigned absoffset = offset + fdt_off_dt_struct(fdt);
> + unsigned int uoffset = offset;
> + unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
> +
> + if (offset < 0)
> + return NULL;
>
> if (!can_assume(VALID_INPUT))
> - if ((absoffset < offset)
> + if ((absoffset < uoffset)
> || ((absoffset + len) < absoffset)
> || (absoffset + len) > fdt_totalsize(fdt))
> return NULL;
>
> if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
> - if (((offset + len) < offset)
> + if (((uoffset + len) < uoffset)
> || ((offset + len) > fdt_size_dt_struct(fdt)))
> return NULL;
>
--
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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