From: Michael Gernoth <michael@gernoth.net>
Date: Sun, 1 Feb 2009 14:56:07 +0000 (+0100)
Subject: better corruption check by calculating the number of fill bytes
X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/rsbs2/commitdiff_plain/b5163e0dbed5fbeb23b9ffa872489c54731c4c3b

better corruption check by calculating the number of fill bytes
---

diff --git a/extract.c b/extract.c
index 1f9c4dd..b420899 100644
--- a/extract.c
+++ b/extract.c
@@ -15,6 +15,7 @@
 struct file_entry* get_next_file(unsigned char *fw, int len)
 {
 	static unsigned char *pos;
+	static unsigned char *start;
 	static unsigned char *end;
 	static struct file_entry fent;
 	int name_length;
@@ -25,6 +26,7 @@ struct file_entry* get_next_file(unsigned char *fw, int len)
 #if 0
 		printf("Start of filesystem: 0x%08x\n", *((unsigned int*)pos));
 #endif
+		start = fw;
 		pos = fw + *((unsigned int*)pos);
 		end = fw + len;
 	}
@@ -32,6 +34,28 @@ struct file_entry* get_next_file(unsigned char *fw, int len)
 	fent.unknown = *pos;
 	pos++;
 
+	if (fent.unknown == 0x00) {
+		/* EOF */
+		int fill = (4 - ((pos - start) % 4)) % 4;
+		int i;
+
+		for (i = 0; i < fill; i++) {
+			if (*pos != 0xff) {
+				fprintf(stderr, "Wrong fill byte after EOF: 0x%02x, aborting!\n", *pos);
+				exit(1);
+			}
+			pos++;
+		}
+
+		if (pos != end) {
+			fprintf(stderr, "EOF marker not at end-of-file %p <-> %p, aborting!\n", pos, end);
+			exit(1);
+		}
+
+		return NULL;
+	}
+
+
 	name_length = *((unsigned int*)pos);
 	pos += 4;
 
@@ -40,10 +64,10 @@ struct file_entry* get_next_file(unsigned char *fw, int len)
 
 	if ((fent.length > (end - pos)) ||
 	    (name_length > (end - pos))) {
-#if 0
-		printf("EOF reached\n");
-#endif
-		return NULL;
+		printf("EOF reached without hitting EOF marker, aborting "
+			"(unknown: 0x%02x, namelen: 0x%08x, contentlen: 0x%08x!\n",
+			fent.unknown, name_length, fent.length);
+		exit(1);
 	}
 
 	fent.name = (char*)pos;
diff --git a/firmware.c b/firmware.c
index 6056111..aeef48c 100644
--- a/firmware.c
+++ b/firmware.c
@@ -345,22 +345,17 @@ int check_crc(unsigned char *fw, int len)
 	return ret;
 }
 
-int check_image(unsigned char *fw, int len)
+void check_image(unsigned char *fw, int len)
 {
 	struct file_entry *fent;
 	char *last_name = NULL;
 
+	/* get_next_file will abort on error */
 	fent = get_next_file(fw, len);
 	while (fent != NULL) {
 		last_name = fent->name;
 		fent = get_next_file(NULL, 0);
 	}
-
-	if (strcmp(last_name, "pdata")) {
-		return 1;
-	}
-
-	return 0;
 }
 
 int main(int argc, char **argv)
@@ -451,15 +446,12 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
-	if (check_image(fw, statbuf.st_size-4) != 0) {
-		fprintf(stderr, "corrupt firmware image found (pdata is not last entry), aborting!\n");
-		exit(1);
-	}
+	check_image(fw, statbuf.st_size - 4);
 
 	if (patch_fw) {
 		struct propaction *cpaction = paction;
 
-		change_properties(fw, statbuf.st_size, paction);
+		change_properties(fw, statbuf.st_size - 4, paction);
 
 		printf("\nProperty change results:\n");
 		while(cpaction != NULL) {
@@ -483,12 +475,12 @@ int main(int argc, char **argv)
 	}
 
 	if (patch_bd) {
-		handle_boarddescription(fw, statbuf.st_size -4, 1);
+		handle_boarddescription(fw, statbuf.st_size - 4, 1);
 	}
 
 	if (showall) {
 		show_properties(fw, statbuf.st_size - 4);
-		handle_boarddescription(fw, statbuf.st_size -4, 0);
+		handle_boarddescription(fw, statbuf.st_size - 4, 0);
 	}
 
 	if (extract) {
@@ -501,10 +493,7 @@ int main(int argc, char **argv)
 			*((unsigned int*)(fw + statbuf.st_size - 4)) = crc;
 		}
 
-		if (check_image(fw, statbuf.st_size-4) != 0) {
-			fprintf(stderr, "corrupt firmware image found (pdata is not last entry), aborting!\n");
-			exit(1);
-		}
+		check_image(fw, statbuf.st_size-4);
 
 		if (check_crc(fw, statbuf.st_size) == 0) {
 			char *newfile;