Fixed: Inspect all IDAT chunks and reject trailing bytes in noWebshellInPNG

The previous implementation returned after the first IDAT chunk, leaving any payload in subsequent IDAT chunks or bytes appended after IEND unreachable. PNG (RFC 2083) explicitly permits multiple IDAT chunks whose data must be concatenated before decompression.

The loop now accumulates all IDAT chunks into a single buffer and terminates on IEND. After IEND, any trailing bytes cause the file to be rejected. inflate() is called once on the fully concatenated payload, as the spec requires.

(cherry picked from commit f8a1118)

Author: jacopoc

framework/security/src/main/java/org/apache/ofbiz/security/SecuredUpload.java

@@ -23,6 +23,7 @@
 import java.awt.Image;
 import java.awt.Transparency;
 import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
 import java.io.DataInputStream;
 import java.io.File;
 import java.io.FileInputStream;
@@ -698,27 +699,39 @@ private static boolean noWebshellInPNG(File file) {
             return false;
         }
 
-        try (DataInputStream stream = new DataInputStream(new FileInputStream(file));) {
-            byte[] data = new byte[8];
-            stream.readFully(data); //Read PNG Header
+        try (DataInputStream stream = new DataInputStream(new FileInputStream(file))) {
+            byte[] header = new byte[8];
+            stream.readFully(header); // Read PNG signature
+            ByteArrayOutputStream idatBuffer = new ByteArrayOutputStream();
+            byte[] nameBuf = new byte[4];
             while (true) {
-                data = new byte[4];
-                stream.readFully(data); //Read Length
-                int length = ((data[0] & 0xFF) << 24)
-                        | ((data[1] & 0xFF) << 16)
-                        | ((data[2] & 0xFF) << 8)
-                        | (data[3] & 0xFF); //Byte array to int
-                stream.readFully(data); //Read Name
-                String name = new String(data); //Byte array to String
+                byte[] lenBuf = new byte[4];
+                stream.readFully(lenBuf); // Read chunk length
+                int length = ((lenBuf[0] & 0xFF) << 24)
+                        | ((lenBuf[1] & 0xFF) << 16)
+                        | ((lenBuf[2] & 0xFF) << 8)
+                        | (lenBuf[3] & 0xFF);
+                stream.readFully(nameBuf); // Read chunk type
+                String name = new String(nameBuf);
                 if (name.equals("IDAT")) {
-                    data = new byte[length];
-                    stream.readFully(data); //Read Data
-                    return inflate(data);
-                } else { //Don't care about other chunks
-                    data = new byte[length + 4]; //Data length + 4 byte CRC
-                    stream.readFully(data); //Skip Data and CRC.
+                    byte[] chunkData = new byte[length];
+                    stream.readFully(chunkData); // Read data
+                    idatBuffer.write(chunkData);
+                    stream.readFully(new byte[4]); // Skip CRC
+                } else if (name.equals("IEND")) {
+                    stream.readFully(new byte[4]); // Skip CRC
+                    break; // IEND marks end of PNG datastream
+                } else {
+                    stream.readFully(new byte[length + 4]); // Skip data and CRC
                 }
             }
+            // Reject any bytes appended after IEND
+            if (stream.read() != -1) {
+                Debug.logError("================== Not saved for security reason, PNG has trailing bytes after IEND ==================", MODULE);
+                return false;
+            }
+            // Inflate all concatenated IDAT chunks
+            return inflate(idatBuffer.toByteArray());
         } catch (IOException error) {
             Debug.logError("================== Not saved for security reason, wrong PNG IDAT (weird) ==================" + error, MODULE);
             return false;