mtdparts: Fix various issues reported by Coverity

Now that sandbox is building cmd/mtdparts.c Coverity has looked at the
code and found a number of issues.  In index_partitions() it is possible
that part will be NULL, so re-work the checks and debug statements to
take this into account.  We have a number of string buffers that we
print to in the exact size of, and use string functions on, so we need
to ensure they are large enough to be NULL terminated.  In
device_parse() it is not possible for num_partitions to be 0 (we would
have hit a different error first) so remove logically dead code.
Finally, in parse_mtdparts() if we have an error we need to free the
memory allocated to dev.

Cc: Lothar Waßmann <LW@KARO-electronics.de>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Reported-by: Coverity (CID: 166334, 166333, 166332, 166329, 166328)
Signed-off-by: Tom Rini <trini@konsulko.com>

cmd/mtdparts.c

@@ -133,9 +133,9 @@ static const char *mtdparts_default = MTDPARTS_DEFAULT;
 #define MTDIDS_MAXLEN		128
 #define MTDPARTS_MAXLEN		512
 #define PARTITION_MAXLEN	16
-static char last_ids[MTDIDS_MAXLEN];
-static char last_parts[MTDPARTS_MAXLEN];
-static char last_partition[PARTITION_MAXLEN];
+static char last_ids[MTDIDS_MAXLEN + 1];
+static char last_parts[MTDPARTS_MAXLEN + 1];
+static char last_partition[PARTITION_MAXLEN + 1];
 
 /* low level jffs2 cache cleaning routine */
 extern void jffs2_free_cache(struct part_info *part);
@@ -240,15 +240,22 @@ static void index_partitions(void)
 			if (dev == current_mtd_dev) {
 				mtddevnum += current_mtd_partnum;
 				env_set_ulong("mtddevnum", mtddevnum);
+				debug("=> mtddevnum %d,\n", mtddevnum);
 				break;
 			}
 			mtddevnum += dev->num_parts;
 		}
 
 		part = mtd_part_info(current_mtd_dev, current_mtd_partnum);
-		env_set("mtddevname", part->name);
+		if (part) {
+			env_set("mtddevname", part->name);
+
+			debug("=> mtddevname %s\n", part->name);
+		} else {
+			env_set("mtddevname", NULL);
 
-		debug("=> mtddevnum %d,\n=> mtddevname %s\n", mtddevnum, part->name);
+			debug("=> mtddevname NULL\n");
+		}
 	} else {
 		env_set("mtddevnum", NULL);
 		env_set("mtddevname", NULL);
@@ -912,12 +919,6 @@ static int device_parse(const char *const mtd_dev, const char **ret, struct mtd_
 		return 1;
 	}
 
-	if (num_parts == 0) {
-		printf("no partitions for device %s%d (%s)\n",
-				MTD_DEV_TYPE(id->type), id->num, id->mtd_id);
-		return 1;
-	}
-
 	debug("\ntotal partitions: %d\n", num_parts);
 
 	/* check for next device presence */
@@ -1593,8 +1594,10 @@ static int parse_mtdparts(const char *const mtdparts)
 		list_add_tail(&dev->link, &devices);
 		err = 0;
 	}
-	if (err == 1)
+	if (err == 1) {
+		free(dev);
 		device_delall(&devices);
+	}
 
 	return err;
 }
@@ -1730,9 +1733,9 @@ int mtdparts_init(void)
 	if (!initialized) {
 		INIT_LIST_HEAD(&mtdids);
 		INIT_LIST_HEAD(&devices);
-		memset(last_ids, 0, MTDIDS_MAXLEN);
-		memset(last_parts, 0, MTDPARTS_MAXLEN);
-		memset(last_partition, 0, PARTITION_MAXLEN);
+		memset(last_ids, 0, sizeof(last_ids));
+		memset(last_parts, 0, sizeof(last_parts));
+		memset(last_partition, 0, sizeof(last_partition));
 #if defined(CONFIG_SYS_MTDPARTS_RUNTIME)
 		board_mtdparts_default(&mtdids_default, &mtdparts_default);
 #endif