[PATCH v6 1/1] image: fit: Apply overlays using aligned writable FDT copies

[Marek Vasut]

On 2/12/26 10:34 PM, James Hilliard wrote:
> libfdt expects FDT/DTO blobs to be 8-byte aligned. When loading the
> base FDT or overlays from a FIT, the mapped buffer may be unaligned,
> which can break fdt_open_into() on strict-alignment architectures.
> 
> boot_get_fdt_fit() relocates the base FDT with boot_relocate_fdt()
> before applying overlays. That uses the bootm memory map and can
> overlap with the FIT buffer when the FIT is loaded into RAM,
> corrupting data needed to load the kernel and ramdisk.
> 
> Allocate writable, 8-byte aligned copies of the base FDT and overlays
> with memalign() and fdt_open_into(). Grow the base buffer as needed,
> apply overlays to it and pack the final tree. Free each temporary
> overlay copy after application and check fdt_pack() errors.
> 
> Fixes: 8fbcc0e0e839 ("boot: Assure FDT is always 8-byte aligned")
> Fixes: 881f0b77dc8c ("image: apply FDTOs on FDT image node")
> Signed-off-by: James Hilliard <james.hilliard1 at gmail.com>
> Cc: Jamie Gibbons <Jamie.Gibbons at microchip.com>
Reviewed-by: Marek Vasut <marek.vasut at mailbox.org>