fexc: Improve script_decompile_bin() safeguards

When declaring 'signed' values for section count and version
information in the script_bin_head structure, testing them to be
below certain thresholds (SCRIPT_BIN_*_LIMIT) is insufficient;
as 'negative' values like in "fexc-bin: script.bin: version:
-404840454.-1074397186.-1073906177" would still pass.

Fix this by making these member fields unsigned.
Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>

script_bin.c

@@ -312,17 +312,16 @@ int script_decompile_bin(void *bin, size_t bin_size,
 			 const char *filename,
 			 struct script *script)
 {
-	int i;
+	unsigned int i;
 	struct script_bin_head *head = bin;
 
-	pr_info("%s: version: %d.%d.%d\n", filename,
-		head->version[0], head->version[1],
-		head->version[2]);
-	pr_info("%s: size: %zu (%d sections)\n", filename,
+	pr_info("%s: version: %u.%u.%u\n", filename,
+		head->version[0], head->version[1], head->version[2]);
+	pr_info("%s: size: %zu (%u sections)\n", filename,
 		bin_size, head->sections);
 
 	if (head->sections > SCRIPT_BIN_SECTION_LIMIT) {
-		pr_err("Malformed data: too many sections (%d).\n",
+		pr_err("Malformed data: too many sections (%u).\n",
 		       head->sections);
 		return 0;
 	}
@@ -330,7 +329,7 @@ int script_decompile_bin(void *bin, size_t bin_size,
 	if ((head->version[0] > SCRIPT_BIN_VERSION_LIMIT) ||
 	    (head->version[1] > SCRIPT_BIN_VERSION_LIMIT) ||
 	    (head->version[2] > SCRIPT_BIN_VERSION_LIMIT)) {
-		pr_err("Malformed data: version %d.%d.%d.\n",
+		pr_err("Malformed data: version %u.%u.%u.\n",
 		       head->version[0], head->version[1], head->version[2]);
 		return 0;
 	}

script_bin.h

@@ -26,8 +26,8 @@ struct script_bin_section {
 
 /** binary representation of the head of the script file */
 struct script_bin_head {
-	int32_t sections;
-	int32_t version[3];
+	uint32_t sections;
+	uint32_t version[3];
 	struct script_bin_section section[];
 };