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More lenient AXML parsing: allow for non-standard attributes sizes and avoid index exceptions when decoding some strings #2210

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merged 2 commits into from
Jul 3, 2024
Merged

More lenient AXML parsing: allow for non-standard attributes sizes and avoid index exceptions when decoding some strings #2210

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b58b1b5
The attributes size of an XML element is now accounted for. This size…
mr-m1j0 Jul 3, 2024
af76eec
Minor code restyling
mr-m1j0 Jul 3, 2024
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11 changes: 7 additions & 4 deletions jadx-core/src/main/java/jadx/core/xmlgen/BinaryXMLParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -265,9 +265,10 @@ private void parseElement() throws IOException {
die("startNS's attributeStart is not 0x14");
}
int attributeSize = is.readInt16();
if (attributeSize != 0x14) {
die("startNS's attributeSize is not 0x14");
if (attributeSize < 0x14) {
die("startNS's attributeSize is less than 0x14");
}

int attributeCount = is.readInt16();
int idIndex = is.readInt16();
int classIndex = is.readInt16();
Expand All @@ -289,22 +290,24 @@ private void parseElement() throws IOException {
Set<String> attrCache = new HashSet<>();
boolean attrNewLine = attributeCount != 1 && this.attrNewLine;
for (int i = 0; i < attributeCount; i++) {
parseAttribute(i, attrNewLine, attrCache);
parseAttribute(i, attrNewLine, attrCache, attributeSize);
}
long endPos = is.getPos();
if (endPos - startPos + 0x4 < elementSize) {
is.skip(elementSize - (endPos - startPos + 0x4));
}
}

private void parseAttribute(int i, boolean newLine, Set<String> attrCache) throws IOException {
private void parseAttribute(int i, boolean newLine, Set<String> attrCache, int attributeSize) throws IOException {
int attributeNS = is.readInt32();
int attributeName = is.readInt32();
int attributeRawValue = is.readInt32();
is.skip(3);
int attrValDataType = is.readInt8();
int attrValData = is.readInt32();

is.skip(attributeSize - 0x14);

String shortNsName = null;
if (attributeNS != -1) {
shortNsName = getAttributeNS(attributeNS, newLine);
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11 changes: 10 additions & 1 deletion jadx-core/src/main/java/jadx/core/xmlgen/BinaryXMLStrings.java
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
import java.util.Map;

public class BinaryXMLStrings {
public static final String INVALID_STRING_PLACEHOLDER = "⟨STRING_DECODE_ERROR⟩";
private final int stringCount;

private final long stringsStart;
Expand Down Expand Up @@ -40,6 +41,10 @@ public String get(int id) {
return cached;
}

if (id * 4 >= buffer.limit() - 3) {
return INVALID_STRING_PLACEHOLDER;
}

long offset = stringsStart + buffer.getInt(id * 4);
String extracted;
if (isUtf8) {
Expand All @@ -63,7 +68,7 @@ public int size() {

private static String extractString8(byte[] strArray, int offset) {
if (offset >= strArray.length) {
return "STRING_DECODE_ERROR";
return INVALID_STRING_PLACEHOLDER;
}
int start = offset + skipStrLen8(strArray, offset);
int len = strArray[start++];
Expand All @@ -78,6 +83,10 @@ private static String extractString8(byte[] strArray, int offset) {
}

private static String extractString16(byte[] strArray, int offset) {
if (offset + 2 >= strArray.length) {
return INVALID_STRING_PLACEHOLDER;
}

int len = strArray.length;
int start = offset + skipStrLen16(strArray, offset);
int end = start;
Expand Down
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