fix: check names from Kotlin metadata before use (#1364)

jadx-core/src/main/java/jadx/core/deobf/ClsAliasPair.java

+package jadx.core.deobf;
+
+public class ClsAliasPair {
+	private final String pkg;
+	private final String name;
+
+	public ClsAliasPair(String pkg, String name) {
+		this.pkg = pkg;
+		this.name = name;
+	}
+
+	public String getPkg() {
+		return pkg;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	@Override
+	public String toString() {
+		return pkg + '.' + name;
+	}
+}

jadx-core/src/main/java/jadx/core/deobf/Deobfuscator.java

@@ -386,10 +386,10 @@ public class Deobfuscator {
 		String alias = null;
 		String pkgName = null;
 		if (this.parseKotlinMetadata) {
-			ClassInfo kotlinCls = KotlinMetadataUtils.getClassName(cls);
+			ClsAliasPair kotlinCls = KotlinMetadataUtils.getClassAlias(cls);
 			if (kotlinCls != null) {
-				alias = prepareNameFull(kotlinCls.getShortName(), "C");
-				pkgName = kotlinCls.getPackage();
+				alias = kotlinCls.getName();
+				pkgName = kotlinCls.getPkg();
 			}
 		}
 		if (alias == null && this.useSourceNameAsAlias) {
@@ -601,20 +601,6 @@ public class Deobfuscator {
 		return NameMapper.removeInvalidCharsMiddle(name);
 	}
 
-	private String prepareNameFull(String name, String prefix) {
-		if (name.length() > maxLength) {
-			return makeHashName(name, prefix);
-		}
-		String result = NameMapper.removeInvalidChars(name, prefix);
-		if (result.isEmpty()) {
-			return makeHashName(name, prefix);
-		}
-		if (NameMapper.isReserved(result)) {
-			return prefix + result;
-		}
-		return result;
-	}
-
 	private static String makeHashName(String name, String invalidPrefix) {
 		return invalidPrefix + 'x' + Integer.toHexString(name.hashCode());
 	}

jadx-core/src/main/java/jadx/core/dex/attributes/nodes/RenameReasonAttr.java

@@ -6,6 +6,16 @@ import jadx.core.dex.attributes.AttrNode;
 
 public class RenameReasonAttr implements IJadxAttribute {
 
+	public static RenameReasonAttr forNode(AttrNode node) {
+		RenameReasonAttr renameReasonAttr = node.get(AType.RENAME_REASON);
+		if (renameReasonAttr != null) {
+			return renameReasonAttr;
+		}
+		RenameReasonAttr newAttr = new RenameReasonAttr();
+		node.addAttr(newAttr);
+		return newAttr;
+	}
+
 	private String description;
 
 	public RenameReasonAttr() {

jadx-core/src/main/java/jadx/core/utils/kotlin/KotlinMetadataUtils.java

@@ -9,8 +9,12 @@ import org.slf4j.LoggerFactory;
 import jadx.api.plugins.input.data.annotations.EncodedType;
 import jadx.api.plugins.input.data.annotations.EncodedValue;
 import jadx.api.plugins.input.data.annotations.IAnnotation;
+import jadx.core.deobf.ClsAliasPair;
+import jadx.core.deobf.NameMapper;
+import jadx.core.dex.attributes.nodes.RenameReasonAttr;
 import jadx.core.dex.info.ClassInfo;
 import jadx.core.dex.nodes.ClassNode;
+import jadx.core.utils.Utils;
 
 // TODO: parse data from d1 (protobuf encoded) to get original method names and other useful info
 public class KotlinMetadataUtils {
@@ -18,13 +22,12 @@ public class KotlinMetadataUtils {
 
 	private static final String KOTLIN_METADATA_ANNOTATION = "Lkotlin/Metadata;";
 	private static final String KOTLIN_METADATA_D2_PARAMETER = "d2";
-	private static final String KOTLIN_METADATA_CLASSNAME_REGEX = "(L.*;)";
 
 	/**
 	 * Try to get class info from Kotlin Metadata annotation
 	 */
 	@Nullable
-	public static ClassInfo getClassName(ClassNode cls) {
+	public static ClsAliasPair getClassAlias(ClassNode cls) {
 		IAnnotation metadataAnnotation = cls.getAnnotation(KOTLIN_METADATA_ANNOTATION);
 		List<EncodedValue> d2Param = getParamAsList(metadataAnnotation, KOTLIN_METADATA_D2_PARAMETER);
 		if (d2Param == null || d2Param.isEmpty()) {
@@ -36,8 +39,14 @@ public class KotlinMetadataUtils {
 		}
 		try {
 			String rawClassName = ((String) firstValue.getValue()).trim();
-			if (rawClassName.matches(KOTLIN_METADATA_CLASSNAME_REGEX)) {
-				return ClassInfo.fromName(cls.root(), rawClassName);
+			if (rawClassName.isEmpty()) {
+				return null;
+			}
+			String clsName = Utils.cleanObjectName(rawClassName);
+			ClsAliasPair alias = splitAndCheckClsName(cls, clsName);
+			if (alias != null) {
+				RenameReasonAttr.forNode(cls).append("from Kotlin metadata");
+				return alias;
 			}
 		} catch (Exception e) {
 			LOG.error("Failed to parse kotlin metadata", e);
@@ -45,6 +54,54 @@ public class KotlinMetadataUtils {
 		return null;
 	}
 
+	// Don't use ClassInfo facility to not pollute class into cache
+	private static ClsAliasPair splitAndCheckClsName(ClassNode originCls, String fullClsName) {
+		if (!NameMapper.isValidFullIdentifier(fullClsName)) {
+			return null;
+		}
+		String pkg;
+		String name;
+		int dot = fullClsName.lastIndexOf('.');
+		if (dot == -1) {
+			pkg = "";
+			name = fullClsName;
+		} else {
+			pkg = fullClsName.substring(0, dot);
+			name = fullClsName.substring(dot + 1);
+		}
+		ClassInfo originClsInfo = originCls.getClassInfo();
+		String originName = originClsInfo.getShortName();
+		if (originName.equals(name)
+				|| name.contains("$")
+				|| !NameMapper.isValidIdentifier(name)
+				|| countPkgParts(originClsInfo.getPackage()) != countPkgParts(pkg)
+				|| pkg.startsWith("java.")) {
+			return null;
+		}
+		ClassNode newClsNode = originCls.root().resolveClass(fullClsName);
+		if (newClsNode != null) {
+			// class with alias name already exist
+			return null;
+		}
+		return new ClsAliasPair(pkg, name);
+	}
+
+	private static int countPkgParts(String pkg) {
+		if (pkg.isEmpty()) {
+			return 0;
+		}
+		int count = 1;
+		int pos = 0;
+		while (true) {
+			pos = pkg.indexOf('.', pos);
+			if (pos == -1) {
+				return count;
+			}
+			pos++;
+			count++;
+		}
+	}
+
 	@SuppressWarnings("unchecked")
 	private static List<EncodedValue> getParamAsList(IAnnotation annotation, String paramName) {
 		if (annotation == null) {

jadx-core/src/test/java/jadx/tests/integration/deobf/TestKotlinMetadata.java

@@ -28,7 +28,8 @@ public class TestKotlinMetadata extends SmaliTest {
 		prepareArgs(true);
 		assertThat(getClassNodeFromSmali())
 				.code()
-				.containsOne("class TestMetaData {");
+				.containsOne("class TestMetaData {")
+				.containsOne("reason: from Kotlin metadata");
 	}
 
 	@Test
@@ -42,6 +43,7 @@ public class TestKotlinMetadata extends SmaliTest {
 	private void prepareArgs(boolean parseKotlinMetadata) {
 		enableDeobfuscation();
 		args.setDeobfuscationMinLength(100); // rename everything
+		args.setDeobfuscationForceSave(true);
 		getArgs().setParseKotlinMetadata(parseKotlinMetadata);
 		disableCompilation();
 	}

jadx-core/src/test/smali/deobf/TestKotlinMetadata.smali

@@ -14,7 +14,7 @@
         "\u0000\u0014\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\u0008\u0002\n\u0002\u0010\u0008\n\u0002\u0008\u0004\u0018\u00002\u00020\u0001B\u0005\u00a2\u0006\u0002\u0010\u0002J\u0015\u0010\u0005\u001a\u00020\u00042\u0006\u0010\u0006\u001a\u00020\u0004H\u0007\u00a2\u0006\u0002\u0008\u0007R\u0010\u0010\u0003\u001a\u00020\u00048\u0006X\u0087D\u00a2\u0006\u0002\n\u0000\u00a8\u0006\u0008"
     }
     d2 = {
-        "LTestMetaData;",
+        "Ljadx/TestMetaData;",
         "",
         "()V",
         "id",