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

[Beleswar Padhi]

From: Marek Vasut <marek.vasut+renesas at mailbox.org>

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 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.

Reported-by: Anshul Dalal <anshuld at ti.com>
Closes: https://lore.kernel.org/u-boot/DFJ950O0QM0D.380U0N16ZO19E@ti.com
Fixes: 0535e46d55d7 ("scripts/dtc: Update to upstream version v1.7.2-35-g52f07dcca47c")
Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
Signed-off-by: Beleswar Padhi <b-padhi at ti.com>
---
Testing Done:
1. Boot tested on all TI K3 platforms.

v4: Changelog:
1. Align only the DTBs to 8-bytes, other images in a FIT can have their
   independent alignment. [Marek]

Link to v3:
https://lore.kernel.org/all/20260122172247.2995437-1-b-padhi@ti.com/

v3: Changelog:
1. Default to 8-byte alignment for DTBs in mkimage instead of
   passing -B 0x8 in build command [Marek]
2. Remove previous R/Bs.

Link to v2:
https://lore.kernel.org/all/20260112101102.1417970-2-b-padhi@ti.com/

v2: Changelog:
1. Carry R/B, Reported-by, Closes and Fixes tag.

Link to v1:
https://lore.kernel.org/all/20260109190026.58464-2-b-padhi@ti.com/

 tools/fit_image.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

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)
+			align_size = 8;
+
 		data = fdt_getprop(fdt, node, FIT_DATA_PROP, &len);
 		if (!data)
 			continue;
-- 
2.34.1