Issue #862 AS3 asm: do not read beyond return/throw instructions

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/AVM2Code.java

@@ -282,6 +282,7 @@ import com.jpexs.decompiler.graph.ScopeStack;
 import com.jpexs.decompiler.graph.TranslateException;
 import com.jpexs.decompiler.graph.TranslateStack;
 import com.jpexs.decompiler.graph.TypeItem;
+import com.jpexs.decompiler.graph.model.ExitItem;
 import com.jpexs.decompiler.graph.model.LocalData;
 import com.jpexs.decompiler.graph.model.ScriptEndItem;
 import com.jpexs.helpers.Helper;
@@ -297,6 +298,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
+import java.util.TreeSet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -675,6 +677,7 @@ public class AVM2Code implements Cloneable {
 
     public AVM2Code(ABCInputStream ais) throws IOException {
         Map<Long, AVM2Instruction> codeMap = new TreeMap<>();
+        Map<Long, Long> endOffsets = new HashMap<>();
         DumpInfo diParent = ais.dumpInfo;
         List<Long> addresses = new ArrayList<>();
         long startPos = ais.getPosition();
@@ -738,6 +741,11 @@ public class AVM2Code implements Cloneable {
                         }
                         codeMap.put(startOffset, new AVM2Instruction(startOffset, instr, actualOperands));
                         ais.endDumpLevel(instr.instructionCode);
+                        long endOffset = ais.getPosition();
+                        endOffsets.put(startOffset, endOffset);
+                        if (instr.isExitInstruction()) { //do not continue if there is return/throw instruction
+                            break;
+                        }
                     } else {
                         ais.endDumpLevel();
                         break; // Unknown instructions are ignored (Some of the obfuscators add unknown instructions)
@@ -750,6 +758,18 @@ public class AVM2Code implements Cloneable {
             }
         }
 
+        //If there are gaps between instructions, fill them with Nops, so the jump offsets are correct
+        List<Long> starts = new ArrayList<>(new TreeSet<>(codeMap.keySet()));
+        for (int s = 0; s < starts.size() - 1/*last does not have next endoffset instruction*/; s++) {
+            long curEnd = endOffsets.get(starts.get(s));
+            if (!codeMap.containsKey(curEnd)) {
+                long nextStart = starts.get(s + 1);
+                for (long off = curEnd; off < nextStart; off++) {
+                    codeMap.put(off, new AVM2Instruction(off, new NopIns(), new int[]{}));
+                }
+            }
+        }
+
         code.addAll(codeMap.values());
     }
 

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/InstructionDefinition.java

@@ -169,4 +169,8 @@ public class InstructionDefinition implements Serializable {
         }
         return true;
     }
+
+    public boolean isExitInstruction() {
+        return false;
+    }
 }

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/other/ReturnValueIns.java

@@ -45,4 +45,10 @@ public class ReturnValueIns extends InstructionDefinition {
     public int getStackDelta(AVM2Instruction ins, ABC abc) {
         return -1;
     }
+
+    @Override
+    public boolean isExitInstruction() {
+        return true;
+    }
+
 }

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/other/ReturnVoidIns.java

@@ -40,4 +40,9 @@ public class ReturnVoidIns extends InstructionDefinition {
     public void translate(boolean isStatic, int scriptIndex, int classIndex, HashMap<Integer, GraphTargetItem> localRegs, TranslateStack stack, ScopeStack scopeStack, AVM2ConstantPool constants, AVM2Instruction ins, List<MethodInfo> method_info, List<GraphTargetItem> output, MethodBody body, ABC abc, HashMap<Integer, String> localRegNames, List<String> fullyQualifiedNames, String path, HashMap<Integer, Integer> localRegsAssignmentIps, int ip, HashMap<Integer, List<Integer>> refs, AVM2Code code) {
         output.add(new ReturnVoidAVM2Item(ins));
     }
+
+    @Override
+    public boolean isExitInstruction() {
+        return true;
+    }
 }

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/other/ThrowIns.java

@@ -45,4 +45,9 @@ public class ThrowIns extends InstructionDefinition {
     public int getStackDelta(AVM2Instruction ins, ABC abc) {
         return -1;
     }
+
+    @Override
+    public boolean isExitInstruction() {
+        return true;
+    }
 }