diff options
| -rw-r--r-- | util/cbfstool/flashmap/fmap.c | 45 |
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; } |