[PATCH v4] tools: fit_image: Fallback to 8-byte alignment for flat_dt images

[Marek Vasut]

On 1/28/26 3:18 PM, Beleswar Padhi wrote:
> From: Marek Vasut <marek.vasut+renesas at mailbox.org>

Please drop this , it isnt needed.

> When CONFIG_SPL_MULTI_DTB_FIT is enabled, multiple device trees are
> packed inside the multidtb.fit FIT image. While the individual DTBs
> and the FIT image start address are 8-byte aligned, the DTBs embedded
> within the FIT image are not guaranteed to maintain 8-byte alignment.
> 
> This misalignment causes -FDT_ERR_ALIGNMENT failure in
> setup_multi_dtb_fit() when locating the next available DTB within the
> FIT blob and setting gd->fdt_blob, because of the recent libfdt
> hardening since commit 0535e46d55d7 ("scripts/dtc: Update to upstream
> version v1.7.2-35-g52f07dcca47c")
> 
> To fix this, check the image type when extracting

"extracting" ? This code changes mkimage, so not "extracting" but 
"packing" (into fitImage), right ?

> FIT image data and
> set the alignment size to 8 bytes (if not already) only for flat_dt
> images. This ensures correct alignment for device tree blobs as per the
> DT spec, while also allowing different alignment sizes for other image
> types within the FIT.

[...]

> diff --git a/tools/fit_image.c b/tools/fit_image.c
> index e865f65a400..f842c845771 100644
> --- a/tools/fit_image.c
> +++ b/tools/fit_image.c
> @@ -682,9 +682,17 @@ static int fit_extract_data(struct image_tool_params *params, const char *fname)
>   	for (node = fdt_first_subnode(fdt, images);
>   	     node >= 0;
>   	     node = fdt_next_subnode(fdt, node)) {
> -		const char *data;
> +		const char *data, *type;
>   		int len;
>   
> +		/* Fallback to 8-byte alignment for DTBs if unaligned */
> +		type = fdt_getprop(fdt, node, FIT_TYPE_PROP, &len);
> +		if (type &&
> +		    len == sizeof("flat_dt") &&
> +		    !memcmp(type, "flat_dt", len) &&
> +		    align_size & 0x7)

What will be the resulting alignment if align_size = 0x1f ? 8 right ? I 
think it should be 0x20 .

> +			align_size = 8;