Bug ID: JDK-8030198 Nashorn: finally-block may execute twice

Type: Bug
Component: core-libs
Sub-Component: jdk.nashorn
Affected Version: 9

Priority: P4
Status: Resolved
Resolution: Duplicate
OS: linux_ubuntu
CPU: generic

Submitted: 2013-12-13
Updated: 2015-03-05
Resolved: 2015-01-28

JDK 9
9Resolved

FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
Incorrect byte code is generated if the try-block ends with a terminal node (except for throw). Combined with a throw statement in the finally block, the finally block will be executed twice.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
jjs> function f() { try { print("try"); return } finally { print("finally"); throw 0 } } f();

Expected: output is "try finally"
Actual: output is "try finally finally"


REPRODUCIBILITY :
This bug can be reproduced always.

This is a P4 bug. There is no need to request deferral. Please remove the 8u20-defer-request and update the FixVersion (indicate what version you do plan to fix, ex: 9, 8u40)
29-05-2014
8u20-defer-request: * Executing finally twice is somewhat higher impact (twice closing a resource for eg). Impact: medium to high * but this code shape is very highly unlikely - extreme corner case. Finally code being executed because of exception thrown or normal path, it is very unlikely that finally throws another exception. Likelihood: very low * There is a simple, clear workaround. Exception can be thrown outside finally block or code can be suitably adjusted easily. Workaround: easy.
29-05-2014
The catch_all block introduced by Lower has a rethrow. The Lower replaces rethrow by finally block code (Lower.spliceFinally -> leaveThrowNode). But, in this example, "try" block has a "return" -- and so "finally" block is "inlined there". Since the "finally" block ends with a "throw", return from try is replaced with print("finally"); throw 0; That "throw 0" is caught by "catch_all" -- which again has print("finally"); throw 0; (as rethrow has also been inlined with finally block code) So, we have "finally" once printed by "return" statement in "try" block. And "catch_all" block also prints "finally" again and throws 0!! Equivalent Java code and compiled code looks as follows: public class Main { public static void main(String[] ar) { f(); } public static void f() { try { System.out.println("try"); return; } finally { System.out.println("finally"); throw new RuntimeException("wrong!"); } } } would be compiled to have "any" type handler as below: public static void main(java.lang.String[]); Code: 0: invokestatic #2 // Method f:()V 3: return public static void f(); Code: 0: getstatic #3 // Field java/lang/System.out:Ljava/io/PrintStream; 3: ldc #4 // String try 5: invokevirtual #5 // Method java/io/PrintStream.println:(Ljava/lang/String;)V 8: getstatic #3 // Field java/lang/System.out:Ljava/io/PrintStream; 11: ldc #6 // String finally 13: invokevirtual #5 // Method java/io/PrintStream.println:(Ljava/lang/String;)V 16: new #7 // class java/lang/RuntimeException 19: dup 20: ldc #8 // String wrong! 22: invokespecial #9 // Method java/lang/RuntimeException."<init>":(Ljava/lang/String;)V 25: athrow 26: astore_0 27: getstatic #3 // Field java/lang/System.out:Ljava/io/PrintStream; 30: ldc #6 // String finally 32: invokevirtual #5 // Method java/io/PrintStream.println:(Ljava/lang/String;)V 35: new #7 // class java/lang/RuntimeException 38: dup 39: ldc #8 // String wrong! 41: invokespecial #9 // Method java/lang/RuntimeException."<init>":(Ljava/lang/String;)V 44: athrow Exception table: from to target type 0 8 26 any <---- any type hander }
20-05-2014
yes - finally block executed twice as described.
17-12-2013

Duplicate :	JDK-8074465 - Nashorn - finally clause executed twice
Duplicate :	JDK-8067139 - Finally blocks inlined incorrectly
Relates :	JDK-8066231 - Fuzzing bug: Invalid symbol slot