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-rw-r--r--util/cbfstool/flashmap/fmap.c45
1 files changed, 39 insertions, 6 deletions
diff --git a/util/cbfstool/flashmap/fmap.c b/util/cbfstool/flashmap/fmap.c
index f143beb90f..f803d6c0da 100644
--- a/util/cbfstool/flashmap/fmap.c
+++ b/util/cbfstool/flashmap/fmap.c
@@ -34,6 +34,7 @@
#define _XOPEN_SOURCE 700
+#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
@@ -69,6 +70,41 @@ int fmap_size(const struct fmap *fmap)
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;
+ /* a basic consistency check: flash should be larger than fmap */
+ if (fmap->size <
+ sizeof(*fmap) + fmap->nareas * sizeof(struct fmap_area))
+ return 0;
+
+ /* fmap-alikes along binary data tend to fail on having a valid,
+ * null-terminated string in the name field.*/
+ int i = 0;
+ while (i < FMAP_STRLEN) {
+ if (fmap->name[i] == 0)
+ break;
+ if (!isalnum(fmap->name[i]))
+ return 0;
+ if (i == FMAP_STRLEN - 1) {
+ /* name is specified to be null terminated. We didn't
+ * break in the 0 test, we didn't fail on the alnum
+ * test, so we're seeing FMAP_STRLEN alphanumerical
+ * symbols, which is one too many.
+ */
+ return 0;
+ }
+ i++;
+ }
+ return 1;
+
+}
+
/* brute force linear search */
static long int fmap_lsearch(const uint8_t *image, size_t len)
{
@@ -76,9 +112,7 @@ static long int fmap_lsearch(const uint8_t *image, size_t len)
int fmap_found = 0;
for (offset = 0; offset < len - strlen(FMAP_SIGNATURE); offset++) {
- if (!memcmp(&image[offset],
- FMAP_SIGNATURE,
- strlen(FMAP_SIGNATURE))) {
+ if (is_valid_fmap((const struct fmap *)&image[offset])) {
fmap_found = 1;
break;
}
@@ -114,9 +148,8 @@ static long int fmap_bsearch(const uint8_t *image, size_t len)
offset += stride) {
if ((offset % (stride * 2) == 0) && (offset != 0))
continue;
- if (!memcmp(&image[offset],
- FMAP_SIGNATURE,
- strlen(FMAP_SIGNATURE))) {
+ if (is_valid_fmap(
+ (const struct fmap *)&image[offset])) {
fmap_found = 1;
break;
}