8050485: super() in a try block in a ctor causes VerifyError

Summary: Parse catch clause paths to ensure they end in throws
Reviewed-by: dlong, acorn, kamg, ctornqvi, lfoltan

src/share/vm/classfile/verifier.cpp

@@ -2231,6 +2231,181 @@ void ClassVerifier::verify_field_instructions(RawBytecodeStream* bcs,
   }
 }
 
+// Look at the method's handlers.  If the bci is in the handler's try block
+// then check if the handler_pc is already on the stack.  If not, push it.
+void ClassVerifier::push_handlers(ExceptionTable* exhandlers,
+                                  GrowableArray<u4>* handler_stack,
+                                  u4 bci) {
+  int exlength = exhandlers->length();
+  for(int x = 0; x < exlength; x++) {
+    if (bci >= exhandlers->start_pc(x) && bci < exhandlers->end_pc(x)) {
+      handler_stack->append_if_missing(exhandlers->handler_pc(x));
+    }
+  }
+}
+
+// Return TRUE if all code paths starting with start_bc_offset end in
+// bytecode athrow or loop.
+bool ClassVerifier::ends_in_athrow(u4 start_bc_offset) {
+  ResourceMark rm;
+  // Create bytecode stream.
+  RawBytecodeStream bcs(method());
+  u4 code_length = method()->code_size();
+  bcs.set_start(start_bc_offset);
+  u4 target;
+  // Create stack for storing bytecode start offsets for if* and *switch.
+  GrowableArray<u4>* bci_stack = new GrowableArray<u4>(30);
+  // Create stack for handlers for try blocks containing this handler.
+  GrowableArray<u4>* handler_stack = new GrowableArray<u4>(30);
+  // Create list of visited branch opcodes (goto* and if*).
+  GrowableArray<u4>* visited_branches = new GrowableArray<u4>(30);
+  ExceptionTable exhandlers(_method());
+
+  while (true) {
+    if (bcs.is_last_bytecode()) {
+      // if no more starting offsets to parse or if at the end of the
+      // method then return false.
+      if ((bci_stack->is_empty()) || ((u4)bcs.end_bci() == code_length))
+        return false;
+      // Pop a bytecode starting offset and scan from there.
+      bcs.set_start(bci_stack->pop());
+    }
+    Bytecodes::Code opcode = bcs.raw_next();
+    u4 bci = bcs.bci();
+
+    // If the bytecode is in a TRY block, push its handlers so they
+    // will get parsed.
+    push_handlers(&exhandlers, handler_stack, bci);
+
+    switch (opcode) {
+      case Bytecodes::_if_icmpeq:
+      case Bytecodes::_if_icmpne:
+      case Bytecodes::_if_icmplt:
+      case Bytecodes::_if_icmpge:
+      case Bytecodes::_if_icmpgt:
+      case Bytecodes::_if_icmple:
+      case Bytecodes::_ifeq:
+      case Bytecodes::_ifne:
+      case Bytecodes::_iflt:
+      case Bytecodes::_ifge:
+      case Bytecodes::_ifgt:
+      case Bytecodes::_ifle:
+      case Bytecodes::_if_acmpeq:
+      case Bytecodes::_if_acmpne:
+      case Bytecodes::_ifnull:
+      case Bytecodes::_ifnonnull:
+        target = bcs.dest();
+        if (visited_branches->contains(bci)) {
+          if (bci_stack->is_empty()) return true;
+          // Pop a bytecode starting offset and scan from there.
+          bcs.set_start(bci_stack->pop());
+        } else {
+          if (target > bci) { // forward branch
+            if (target >= code_length) return false;
+            // Push the branch target onto the stack.
+            bci_stack->push(target);
+            // then, scan bytecodes starting with next.
+            bcs.set_start(bcs.next_bci());
+          } else { // backward branch
+            // Push bytecode offset following backward branch onto the stack.
+            bci_stack->push(bcs.next_bci());
+            // Check bytecodes starting with branch target.
+            bcs.set_start(target);
+          }
+          // Record target so we don't branch here again.
+          visited_branches->append(bci);
+        }
+        break;
+
+      case Bytecodes::_goto:
+      case Bytecodes::_goto_w:
+        target = (opcode == Bytecodes::_goto ? bcs.dest() : bcs.dest_w());
+        if (visited_branches->contains(bci)) {
+          if (bci_stack->is_empty()) return true;
+          // Been here before, pop new starting offset from stack.
+          bcs.set_start(bci_stack->pop());
+        } else {
+          if (target >= code_length) return false;
+          // Continue scanning from the target onward.
+          bcs.set_start(target);
+          // Record target so we don't branch here again.
+          visited_branches->append(bci);
+        }
+        break;
+
+      // Check that all switch alternatives end in 'athrow' bytecodes. Since it
+      // is  difficult to determine where each switch alternative ends, parse
+      // each switch alternative until either hit a 'return', 'athrow', or reach
+      // the end of the method's bytecodes.  This is gross but should be okay
+      // because:
+      // 1. tableswitch and lookupswitch byte codes in handlers for ctor explicit
+      //    constructor invocations should be rare.
+      // 2. if each switch alternative ends in an athrow then the parsing should be
+      //    short.  If there is no athrow then it is bogus code, anyway.
+      case Bytecodes::_lookupswitch:
+      case Bytecodes::_tableswitch:
+        {
+          address aligned_bcp = (address) round_to((intptr_t)(bcs.bcp() + 1), jintSize);
+          u4 default_offset = Bytes::get_Java_u4(aligned_bcp) + bci;
+          int keys, delta;
+          if (opcode == Bytecodes::_tableswitch) {
+            jint low = (jint)Bytes::get_Java_u4(aligned_bcp + jintSize);
+            jint high = (jint)Bytes::get_Java_u4(aligned_bcp + 2*jintSize);
+            // This is invalid, but let the regular bytecode verifier
+            // report this because the user will get a better error message.
+            if (low > high) return true;
+            keys = high - low + 1;
+            delta = 1;
+          } else {
+            keys = (int)Bytes::get_Java_u4(aligned_bcp + jintSize);
+            delta = 2;
+          }
+          // Invalid, let the regular bytecode verifier deal with it.
+          if (keys < 0) return true;
+
+          // Push the offset of the next bytecode onto the stack.
+          bci_stack->push(bcs.next_bci());
+
+          // Push the switch alternatives onto the stack.
+          for (int i = 0; i < keys; i++) {
+            u4 target = bci + (jint)Bytes::get_Java_u4(aligned_bcp+(3+i*delta)*jintSize);
+            if (target > code_length) return false;
+            bci_stack->push(target);
+          }
+
+          // Start bytecode parsing for the switch at the default alternative.
+          if (default_offset > code_length) return false;
+          bcs.set_start(default_offset);
+          break;
+        }
+
+      case Bytecodes::_return:
+        return false;
+
+      case Bytecodes::_athrow:
+        {
+          if (bci_stack->is_empty()) {
+            if (handler_stack->is_empty()) {
+              return true;
+            } else {
+              // Parse the catch handlers for try blocks containing athrow.
+              bcs.set_start(handler_stack->pop());
+            }
+          } else {
+            // Pop a bytecode offset and starting scanning from there.
+            bcs.set_start(bci_stack->pop());
+          }
+        }
+        break;
+
+      default:
+        ;
+    } // end switch
+  } // end while loop
+
+  return false;
+}
+
 void ClassVerifier::verify_invoke_init(
     RawBytecodeStream* bcs, u2 ref_class_index, VerificationType ref_class_type,
     StackMapFrame* current_frame, u4 code_length, bool *this_uninit,
@@ -2250,18 +2425,26 @@ void ClassVerifier::verify_invoke_init(
       return;
     }
 
-    // Make sure that this call is not done from within a TRY block because
-    // that can result in returning an incomplete object.  Simply checking
-    // (bci >= start_pc) also ensures that this call is not done after a TRY
-    // block.  That is also illegal because this call must be the first Java
-    // statement in the constructor.
+    // Check if this call is done from inside of a TRY block.  If so, make
+    // sure that all catch clause paths end in a throw.  Otherwise, this
+    // can result in returning an incomplete object.
     ExceptionTable exhandlers(_method());
     int exlength = exhandlers.length();
     for(int i = 0; i < exlength; i++) {
-      if (bci >= exhandlers.start_pc(i)) {
-        verify_error(ErrorContext::bad_code(bci),
-                     "Bad <init> method call from after the start of a try block");
-        return;
+      u2 start_pc = exhandlers.start_pc(i);
+      u2 end_pc = exhandlers.end_pc(i);
+
+      if (bci >= start_pc && bci < end_pc) {
+        if (!ends_in_athrow(exhandlers.handler_pc(i))) {
+          verify_error(ErrorContext::bad_code(bci),
+            "Bad <init> method call from after the start of a try block");
+          return;
+        } else if (VerboseVerification) {
+          ResourceMark rm;
+          tty->print_cr(
+            "Survived call to ends_in_athrow(): %s",
+                        current_class()->name()->as_C_string());
+        }
       }
     }
 

src/share/vm/classfile/verifier.hpp

@@ -30,6 +30,7 @@
 #include "oops/klass.hpp"
 #include "oops/method.hpp"
 #include "runtime/handles.hpp"
+#include "utilities/growableArray.hpp"
 #include "utilities/exceptions.hpp"
 
 // The verifier class
@@ -303,6 +304,16 @@ class ClassVerifier : public StackObj {
     StackMapFrame* current_frame, u4 code_length, bool* this_uninit,
     constantPoolHandle cp, TRAPS);
 
+  // Used by ends_in_athrow() to push all handlers that contain bci onto
+  // the handler_stack, if the handler is not already on the stack.
+  void push_handlers(ExceptionTable* exhandlers,
+                     GrowableArray<u4>* handler_stack,
+                     u4 bci);
+
+  // Returns true if all paths starting with start_bc_offset end in athrow
+  // bytecode or loop.
+  bool ends_in_athrow(u4 start_bc_offset);
+
   void verify_invoke_instructions(
     RawBytecodeStream* bcs, u4 code_length, StackMapFrame* current_frame,
     bool* this_uninit, VerificationType return_type,