[squash] livepatch/klp-convert: fix klp-convert off-by-one sympos

Note: squash with ("livepatch: Add klp-convert tool")

There is a small bug in valid_sympos() when sympos > 0 and when the
the position is the last obj:sym in the set.

When there is a lone obj:sym name, we should expect its sympos=0,
however, when there are multiple obj:sym names found, its sympos
specifies the symbol indexed from 1 (not 0).

Split these two cases up to clarify the code. In addition to fixing the
above case, also strengthen the sympos=0 case by verifying that there is
indeed only a single obj:sym name found.

[joe: separate and fix valid_sympos() sympos=0 and !=0 checks]

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>

scripts/livepatch/klp-convert.c

@@ -328,19 +328,47 @@ static struct symbol_entry *find_sym_entry_by_name(char *name)
 static bool valid_sympos(struct sympos *sp)
 {
 	struct symbol_entry *e;
-	int counter = 0;
 
-	list_for_each_entry(e, &symbols, list) {
-		if ((strcmp(e->symbol_name, sp->symbol_name) == 0) &&
-		    (strcmp(e->object_name, sp->object_name) == 0)) {
-			if (counter == sp->pos)
-				return true;
-			counter++;
+	if (sp->pos == 0) {
+
+		/*
+		 * sympos of 0 is reserved for uniquely named obj:sym,
+		 * verify that this is the case
+		 */
+		int counter = 0;
+		list_for_each_entry(e, &symbols, list) {
+			if ((strcmp(e->symbol_name, sp->symbol_name) == 0) &&
+			    (strcmp(e->object_name, sp->object_name) == 0)) {
+				counter++;
+			}
+		}
+		if (counter == 1)
+			return true;
+
+		WARN("Provided KLP_SYMPOS of 0, but found %d symbols matching: %s.%s,%d",
+				counter, sp->object_name, sp->symbol_name,
+				sp->pos);
+
+	} else {
+
+		/*
+		 * sympos > 0 indicates a specific commonly-named obj:sym,
+		 * indexing starts with 1
+		 */
+		int index = 1;
+		list_for_each_entry(e, &symbols, list) {
+			if ((strcmp(e->symbol_name, sp->symbol_name) == 0) &&
+			    (strcmp(e->object_name, sp->object_name) == 0)) {
+				if (index == sp->pos)
+					return true;
+				index++;
+			}
 		}
+
+		WARN("Provided KLP_SYMPOS does not match a symbol: %s.%s,%d",
+				sp->object_name, sp->symbol_name, sp->pos);
 	}
 
-	WARN("Provided KLP_SYMPOS does not match a symbol: %s.%s,%d",
-			sp->object_name, sp->symbol_name, sp->pos);
 	print_valid_module_relocs(sp->symbol_name);
 
 	return false;