The code now checks for consistency of the MCU sizes across

hierarchical levels, and fails in case they are different.

README

@@ -460,6 +460,8 @@ out-of-bounds symbol triggered and out-of-bounds array access and could
 have crashed the decoder. The code is now more carefully changing the
 validity of the symbols and aborts with an error if it finds illegal
 codes.
+The code now also checks the consistency of the MCU sizes in the
+hierarchical process and fails if they differ across levels.
 
 --------------------------------------------------------------------------
 

README.history

@@ -564,5 +564,7 @@ out-of-bounds symbol triggered and out-of-bounds array access and could
 have crashed the decoder. The code is now more carefully changing the
 validity of the symbols and aborts with an error if it finds illegal
 codes.
+The code now also checks the consistency of the MCU sizes in the
+hierarchical process and fails if they differ across levels.
 
 --------------------------------------------------------------------------

control/hierarchicalbitmaprequester.cpp

@@ -45,7 +45,7 @@
 ** decoding. It also keeps the top-level color transformer and the
 ** toplevel subsampling expander.
 **
-** $Id: hierarchicalbitmaprequester.cpp,v 1.42 2020/04/08 10:05:41 thor Exp $
+** $Id: hierarchicalbitmaprequester.cpp,v 1.43 2022/05/24 05:42:35 thor Exp $
 **
 */
 
@@ -245,6 +245,16 @@ void HierarchicalBitmapRequester::PrepareForDecoding(void)
       UBYTE sx = comp->SubXOf();
       UBYTE sy = comp->SubYOf();
 
+      if (m_pLargestScale) {
+        class Frame *frame = m_pLargestScale->FrameOf();
+        while(frame) {
+          if (frame->ComponentOf(i)->SubXOf() != sx || frame->ComponentOf(i)->SubYOf() != sy)
+            JPG_THROW(MALFORMED_STREAM,"HierarchicalBitmapRequester::PrepareForDecoding",
+                      "component subsampling is inconsistent across hierarchical levels");
+          frame = frame->NextOf();
+        }
+      }
+
       if (sx > 1 || sy > 1) {
         m_ppUpsampler[i] = UpsamplerBase::CreateUpsampler(m_pEnviron,sx,sy,
                                                           m_ulPixelWidth,m_ulPixelHeight,