boot_get_fdt_fit_into_buffer() calls fdt_open_into() for both the
base FDT and overlay DTO blobs loaded from a FIT image.
Those blobs come from FIT payload data. In the overlay path,
fit_image_load() is called with FIT_LOAD_IGNORED, so the IH_TYPE_FLATDT
header check in fit_image_load() is skipped. This leaves fdt_open_into()
to consume header-derived offsets/sizes from unvalidated input.
Validate the full blob against the payload length first with
fdt_check_full(fdtsrcbuf, srclen), then proceed with fdt_totalsize() and
fdt_open_into(). This fixes Coverity CID 644638 (TAINTED_SCALAR).
Fixes: 5ebf0c55a23 ("image: fit: Apply overlays using aligned writable FDT
copies")
Link: https://lore.kernel.org/all/20260223195109.GG3233182@bill-the-cat/
Signed-off-by: James Hilliard <[email protected]>
---
boot/image-fit.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/boot/image-fit.c b/boot/image-fit.c
index ddc64debb14..e7c7212195f 100644
--- a/boot/image-fit.c
+++ b/boot/image-fit.c
@@ -2390,6 +2390,14 @@ static int boot_get_fdt_fit_into_buffer(const void *src,
ulong srclen,
fdtsrcbuf = tmp;
}
+ /*
+ * Source data comes from FIT payload. Validate the blob against
+ * payload length before fdt_open_into() trusts header offsets/sizes.
+ */
+ err = fdt_check_full(fdtsrcbuf, srclen);
+ if (err < 0)
+ goto out;
+
newdstlen = ALIGN(fdt_totalsize(fdtsrcbuf) + extra, SZ_4K);
min_dstlen = ALIGN(min_dstlen, SZ_4K);
if (newdstlen < min_dstlen)
--
2.43.0
