8292317: Missing null check for Iterator.forEachRemaining implementations #11154

jaikiran · 2022-11-15T02:10:01Z

Can I please get a review of this change which proposes to fix https://bugs.openjdk.org/browse/JDK-8292317?

The java.util.Iterator has a forEachRemaining(Consumer<? super E> action) method. As per its contract, the implementations are expected to throw a NullPointerException if the passed action is null.

java.util.Collections has a couple of places where it wraps the passed action into another and passes that wrapped action to the underlying java.util.Iterator's default forEachRemaining implementation which is:

Objects.requireNonNull(action);
  while (hasNext())
      action.accept(next());

Since the passed action is now a non-null wrapper, the implementation goes ahead and advances the iterator to the next entry and invokes on the non-null action to carry out its action. That non-null wrapper action then calls the null user passed action and runs into an expected NullPointerException. However, at this point the iterator has already advanced and that is what the bug is.

The commit in this PR introduces a trivial null check on the action very early in the call even before wrapping such an action. This prevents any further logic to execute if action is null.

New test methods have been added to the existing test class test/jdk/java/util/Collections/DelegatingIteratorForEachRemaining.java. This test class was introduced in https://bugs.openjdk.org/browse/JDK-8205184 where this delegation logic was added for the forEachRemaining methods. These new test methods reproduce the failure and verify the fix.

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Issue

JDK-8292317: Missing null check for Iterator.forEachRemaining implementations

Reviewers

Athijegannathan Sundararajan (@sundararajana - Reviewer) ⚠️ Review applies to b58984ec
Stuart Marks (@stuart-marks - Reviewer)

Reviewing

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$ git checkout pull/11154

Update a local copy of the PR:
$ git checkout pull/11154
$ git pull https://git.openjdk.org/jdk pull/11154/head

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Checkout this PR locally:
$ git pr checkout 11154

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…ions

bridgekeeper · 2022-11-15T02:10:26Z

👋 Welcome back jpai! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2022-11-15T02:13:05Z

@jaikiran The following label will be automatically applied to this pull request:

core-libs

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mlbridge · 2022-11-15T02:16:34Z

Webrevs

01: Full - Incremental (ff4c2613)
00: Full (b58984ec)

sundararajana

LGTM

openjdk · 2022-11-15T03:19:03Z

@jaikiran This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8292317: Missing null check for Iterator.forEachRemaining implementations

Reviewed-by: sundar, smarks

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 103 new commits pushed to the master branch:

52494df: 8290845: Consider an alternative item separator for multi-item option values
c56c69e: 8285604: closed sun/java2d/GdiRendering/ClipShapeRendering.java failed with "Incorrect color ffeeeeee instead of ff0000ff in pixel (100, 100)"
6fd1442: 8296743: Tighten Class.getModifiers spec for array classes
3a15e84: 8297258: Typo in java -help referencing -disable-@files instead of --disable-@files
43ce047: 8178698: javax/sound/midi/Sequencer/MetaCallback.java failed with timeout
035eaee: 8296324: JVMTI GetStackTrace truncates vthread stack trace for agents loaded into running VM
59a308b: 8296632: Write a test to verify the content change of TextArea sends TextEvent
11fc65f: 8023562: [TEST_BUG] java/awt/Mouse/EnterExitEvents/DragWindowTest.java failed on ubuntu 13 and mac 10.11
2c692aa: 8297088: Update LCMS to 2.14
9b4e0e8: 8297080: Remove com/sun/jdi/NashornPopFrameTest.java from the problem list
... and 93 more: https://git.openjdk.org/jdk/compare/873eccde01895de06e2216f6838d52d07188addd...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

stuart-marks · 2022-11-17T03:39:37Z

test/jdk/java/util/Collections/DelegatingIteratorForEachRemaining.java

+        Assert.assertThrows(NullPointerException.class, () -> it.forEachRemaining(null));
+        // verify the iterator didn't advance
+        Assert.assertTrue("Iterator unexpectedly doesn't have any entry", it.hasNext());
+    }


The checks in Collections.java look good.

The tests can be simplified, I think. The reproducers in the original bug report wrap an empty map in either an unmodifiable map or a checked map, so you could just test them with entrySet().iterator().forEachRemaining(null). Those cases do nothing in the current JDK when they indeed should throw NPE. Probably just test for NPE thrown/not-thrown instead of trying to ascertain the position of the iterator.

Hello Stuart, I have now updated the PR to simplify the test as suggested. New test methods continue to fail without the source change and pass with this fix.

jaikiran · 2022-11-17T09:05:29Z

tier1, tier2, tier3 and java_util tests in JCK have passed with this change.

Marcono1234 · 2022-11-17T20:15:55Z

src/java.base/share/classes/java/util/Collections.java

+                        Objects.requireNonNull(action);
                        i.forEachRemaining(entryConsumer(action));


As pointed out in the bug report description, it might be better to add the null check to entryConsumer. That would avoid code duplication for the null checks for all the current callers of entryConsumer.

(This comment only applies here; for CheckedEntrySet below this does not work because it does not call entryConsumer.)

Hello @Marcono1234, I prefer doing it earliest in the top level method (which specifies the contract) instead of doing it in an internal method that this method calls.

stuart-marks

Updated tests look good, thanks.

jaikiran · 2022-11-19T00:53:38Z

Thank you everyone for the reviews and the suggestions.

jaikiran · 2022-11-19T00:53:43Z

/integrate

openjdk · 2022-11-19T00:55:26Z

Going to push as commit 906f1ca.
Since your change was applied there have been 105 commits pushed to the master branch:

0ec575a: 8297289: problem list runtime/vthread/RedefineClass.java and TestObjectAllocationSampleEvent.java
dcb8375: 8245246: Deprecate -profile option in javac
52494df: 8290845: Consider an alternative item separator for multi-item option values
c56c69e: 8285604: closed sun/java2d/GdiRendering/ClipShapeRendering.java failed with "Incorrect color ffeeeeee instead of ff0000ff in pixel (100, 100)"
6fd1442: 8296743: Tighten Class.getModifiers spec for array classes
3a15e84: 8297258: Typo in java -help referencing -disable-@files instead of --disable-@files
43ce047: 8178698: javax/sound/midi/Sequencer/MetaCallback.java failed with timeout
035eaee: 8296324: JVMTI GetStackTrace truncates vthread stack trace for agents loaded into running VM
59a308b: 8296632: Write a test to verify the content change of TextArea sends TextEvent
11fc65f: 8023562: [TEST_BUG] java/awt/Mouse/EnterExitEvents/DragWindowTest.java failed on ubuntu 13 and mac 10.11
... and 95 more: https://git.openjdk.org/jdk/compare/873eccde01895de06e2216f6838d52d07188addd...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-11-19T00:55:40Z

@jaikiran Pushed as commit 906f1ca.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8292317: Missing null check for Iterator.forEachRemaining implementat…

b58984e

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openjdk bot added the rfr Pull request is ready for review label Nov 15, 2022

openjdk bot added the core-libs core-libs-dev@openjdk.org label Nov 15, 2022

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openjdk bot added the ready Pull request is ready to be integrated label Nov 15, 2022

stuart-marks reviewed Nov 17, 2022

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review suggestion - simplify test

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Marcono1234 reviewed Nov 17, 2022

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stuart-marks approved these changes Nov 18, 2022

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jaikiran deleted the 8292317 branch November 8, 2024 04:15

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8292317: Missing null check for Iterator.forEachRemaining implementations #11154

8292317: Missing null check for Iterator.forEachRemaining implementations #11154

jaikiran commented Nov 15, 2022 •

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openjdk bot commented Nov 19, 2022

		Objects.requireNonNull(action);
		i.forEachRemaining(entryConsumer(action));

8292317: Missing null check for Iterator.forEachRemaining implementations #11154

8292317: Missing null check for Iterator.forEachRemaining implementations #11154

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jaikiran commented Nov 15, 2022 • edited by openjdk bot Loading

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