device_tree: Add version checks
This patch adds a few more sanity checks to the FDT header parsing to
make sure that our code can support the version that is passed in.
This patch was adapted from depthcharge's http://crosreview.com/1536384
Change-Id: I06c112f540213c8db7c2455c2e8a4e8e4f337b78
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32862
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/lib/device_tree.c b/src/lib/device_tree.c
index bb40eee..7a3128e 100644
--- a/src/lib/device_tree.c
+++ b/src/lib/device_tree.c
@@ -220,6 +220,24 @@
const struct fdt_header *header = (const struct fdt_header *)blob;
tree->header = header;
+ uint32_t magic = be32toh(header->magic);
+ uint32_t version = be32toh(header->version);
+ uint32_t last_comp_version = be32toh(header->last_comp_version);
+
+ if (magic != FDT_HEADER_MAGIC) {
+ printk(BIOS_DEBUG, "Invalid device tree magic %#.8x!\n", magic);
+ return NULL;
+ }
+ if (last_comp_version > FDT_SUPPORTED_VERSION) {
+ printk(BIOS_DEBUG, "Unsupported device tree version %u(>=%u)\n",
+ version, last_comp_version);
+ return NULL;
+ }
+ if (version > FDT_SUPPORTED_VERSION)
+ printk(BIOS_DEBUG,
+ "NOTE: FDT version %u too new, should add support!\n",
+ version);
+
uint32_t struct_offset = be32toh(header->structure_offset);
uint32_t strings_offset = be32toh(header->strings_offset);
uint32_t reserve_offset = be32toh(header->reserve_map_offset);