From 556ec4fd6089cc54dc06902d9c4e1831609332a5 Mon Sep 17 00:00:00 2001
From: Hung-Te Lin <hungte@chromium.org>
Date: Thu, 20 Jun 2013 10:32:48 +0800
Subject: dump_fmap: Find correct FMAP structure by checking version.

Firmware images reading its own FMAP structure may have FMAP signature in code
and cause dump_fmap to parse incorrectly. Since currently there is only one
major version for FMAP (and the structure defined in fmap.h also applies only to
current version), we can improve that by checking major version number to skip
signatures in firmware code.

BUG=chromium:236347
TEST=emerge vboot_reference; dump_fmap /build/daisy/firmware/image.bin # success
BRANCH=none

Change-Id: I1d8f49bb88357e7a3a945fbdba9d9a7c4e177ac4
Reviewed-on: https://gerrit.chromium.org/gerrit/59362
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
---
 host/lib/fmap.c         | 11 ++++++++---
 host/lib/include/fmap.h |  1 +
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/host/lib/fmap.c b/host/lib/fmap.c
index 3c3f340b..014c97b2 100644
--- a/host/lib/fmap.c
+++ b/host/lib/fmap.c
@@ -12,10 +12,15 @@
 const char* FmapFind(const char* ptr, size_t size)
 {
   size_t i;
-  for (i=0; i<size; i += FMAP_SEARCH_STRIDE) {
-    if (0 == strncmp(ptr, FMAP_SIGNATURE, FMAP_SIGNATURE_SIZE))
+  FmapHeader *fmap_header;
+  for (i=0; i<size; i += FMAP_SEARCH_STRIDE, ptr += FMAP_SEARCH_STRIDE) {
+    if (0 != strncmp(ptr, FMAP_SIGNATURE, FMAP_SIGNATURE_SIZE))
+      continue;
+    // Image may have multiple signatures (ex, in code that handles FMAP itself)
+    // so we do want to check at least major version.
+    fmap_header = (FmapHeader *)ptr;
+    if (fmap_header->fmap_ver_major == FMAP_VER_MAJOR)
       return ptr;
-    ptr += FMAP_SEARCH_STRIDE;
   }
   return NULL;
 }
diff --git a/host/lib/include/fmap.h b/host/lib/include/fmap.h
index 7da2dd90..92d74fd3 100644
--- a/host/lib/include/fmap.h
+++ b/host/lib/include/fmap.h
@@ -15,6 +15,7 @@
 #define FMAP_SIGNATURE "__FMAP__"
 #define FMAP_SIGNATURE_SIZE 8
 #define FMAP_SEARCH_STRIDE 4
+#define FMAP_VER_MAJOR 1
 typedef struct _FmapHeader {
   char        fmap_signature[FMAP_SIGNATURE_SIZE]; /* avoiding endian issues */
   uint8_t     fmap_ver_major;
-- 
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