[XS] Change in flashrom[main]: fmap: Update major/minor version check

[Anastasia Klimchuk (Code Review)]

Anastasia Klimchuk has submitted this change. ( https://review.coreboot.org/c/flashrom/+/79060?usp=email )

Change subject: fmap: Update major/minor version check
......................................................................

fmap: Update major/minor version check

It's not valid to separately check the major and minor versions. The
proper minor check would be something like:

if (fmap->ver_major == FMAP_VER_MAJOR &&
      fmap->ver_minor > FMAP_VER_MINOR)
    ERROR();

But this code was alleged (at introduction in [1]) to have come from
cbfstool, and cbfstool doesn't bother with a minor version check. This
check is only for finding the FMAP while searching the flash; it isn't
actually here for integrity and compatibility purpose.

Drop the MINOR version check; align with cbfstool on the MAJOR version
check; and match the cbfstool comments for is_valid_fmap(), to emphasize
the lack of precision.

[1] Commit c82900b66142 ("Add support to get layout from fmap (e.g.
    coreboot rom)")

BRANCH=none
BUG=b:288327526
TEST=libflashrom + ChromiumOS flashmap

Change-Id: I984835579d3b257a2462906f1f5091b179891bd0
Signed-off-by: Brian Norris 
Reviewed-on: https://review.coreboot.org/c/flashrom/+/79060
Tested-by: build bot (Jenkins) 
Reviewed-by: Anastasia Klimchuk 
---
M fmap.c
1 file changed, 2 insertions(+), 3 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Anastasia Klimchuk: Looks good to me, approved

diff --git a/fmap.c b/fmap.c
index 7f5df2b..50cb969 100644
--- a/fmap.c
+++ b/fmap.c
@@ -47,14 +47,13 @@
    return sizeof(*fmap) + (fmap->nareas * sizeof(struct fmap_area));
 }

+/* Make a best-effort assessment if the given fmap is real */
 static int is_valid_fmap(const struct fmap *fmap)
 {
    if (memcmp(fmap, FMAP_SIGNATURE, strlen(FMAP_SIGNATURE)) != 0)
    	return 0;
    /* strings containing the magic tend to fail here */
-	if (fmap->ver_major > FMAP_VER_MAJOR)
-		return 0;
-	if (fmap->ver_minor > FMAP_VER_MINOR)
+	if (fmap->ver_major != FMAP_VER_MAJOR)
    	return 0;
    /* a basic consistency check: flash address space size should be larger
     * than the size of the fmap data structure */