8360664: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object() #26002

savoptik · 2025-06-26T13:24:31Z

The defect has been detected and confirmed in the function IterateOverHeapObjectClosure::do_object() located in the file src/hotspot/share/prims/jvmtiTagMap.cpp with static code analysis. This defect can potentially lead to a null pointer dereference.

The pointer oop o is passed to the constructor of the CallbackWrapper class, where it is dereferenced without a null check.

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Issue

JDK-8360664: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object() (Bug - P4)

Reviewers

Alex Menkov (@alexmenkov - Reviewer) Review applies to 88f1e494
Chris Plummer (@plummercj - Reviewer) Review applies to 88f1e494
Serguei Spitsyn (@sspitsyn - Reviewer)

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bridgekeeper · 2025-06-26T13:25:21Z

👋 Welcome back asemenov! 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 · 2025-06-26T13:25:23Z

@savoptik 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:

8360664: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object()

Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Artem Semenov <savoptik@altlinux.org>.

Reviewed-by: sspitsyn, amenkov, cjplummer

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 72 new commits pushed to the master branch:

74822ce: 8358183: [JVMCI] crash accessing nmethod::jvmci_name in CodeCache::aggregate
ea86a20: 8357424: [JVMCI] Avoid incrementing decompilation count for hosted compiled nmethod
5e30bf6: 8360116: Add support for AVX10 floating point minmax instruction
... and 69 more: https://git.openjdk.org/jdk/compare/5039b42de170769797312969185ee9d67f34cf24...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.

openjdk · 2025-06-26T13:26:01Z

@savoptik The following labels will be automatically applied to this pull request:

hotspot
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When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

mlbridge · 2025-06-26T13:28:43Z

Webrevs

savoptik · 2025-06-26T13:40:19Z

/issue add 8360670

openjdk · 2025-06-26T13:40:53Z

@savoptik
Adding additional issue to issue list: 8360670: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateThroughHeapObjectClosure::do_object().

…ap.cpp in IterateOverHeapObjectClosure::do_object() Found by Linux Verification Center (linuxtesting.org) with SVACE. signed-off-by: Artem Semenov <savoptik@altlinux.org>

openjdk · 2025-06-26T13:58:08Z

@savoptik Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

plummercj · 2025-06-26T15:41:16Z

It's concerning that we don't have tests cases that uncover these bugs. Perhaps it's not actually possible for NULL to be passed when constructing CallbackWrapper.

dholmes-ora

I think this is a false positive from the static code analyzer. If we are iterating over the heap then the closure is only ever passed actual oops, so it can't be null.

At most I would add an assert, but generally my understanding is that the user of any closure has the responsibility of passing it valid input.

sspitsyn · 2025-06-27T05:22:00Z

At most I would add an assert, but generally my understanding is that the user of any closure has the responsibility of passing it valid input.

Adding asserts sounds like a good suggestion.

sspitsyn · 2025-06-27T05:26:42Z

I'm a little bit confused why we have twp bugs for this issue.
The bug JDK-8360670 seems to be a dup of:
JDK-8360664: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object()
Should it be closed as a dup?

savoptik · 2025-06-27T12:06:21Z

At most I would add an assert, but generally my understanding is that the user of any closure has the responsibility of passing it valid input.

Adding asserts sounds like a good suggestion.

It seems to me that this won’t be a big problem in this form. I’ve just moved the existing check higher up, where it will prevent dereferencing a null pointer.

However, if you confirm that this is not acceptable, I will replace the check with assert.

plummercj · 2025-06-27T17:28:43Z

At most I would add an assert, but generally my understanding is that the user of any closure has the responsibility of passing it valid input.

Adding asserts sounds like a good suggestion.

It seems to me that this won’t be a big problem in this form. I’ve just moved the existing check higher up, where it will prevent dereferencing a null pointer.

However, if you confirm that this is not acceptable, I will replace the check with assert.

I think it is a matter of having the code accurately document the input requirements. Checking for null and returning makes it look like passing null is ok and might happen. That's not the case though. It should never happen and adding an assert properly documents this.

plummercj

The fix looks good, but I assume that the static analysis tool that reported the false warning is still going to report it, or at least do so in product builds where the assert code is not included.

dholmes-ora · 2025-07-01T03:13:06Z

src/hotspot/share/prims/jvmtiTagMap.cpp


 // invoked for each object in the heap
 void IterateOverHeapObjectClosure::do_object(oop o) {
+  assert(o != nullptr, "Parameter 'o' must not be null!");


Suggested change

assert(o != nullptr, "Parameter 'o' must not be null!");

assert(o != nullptr, "Heap iteration should never produce null");

Same with the other assertion please. Though as @plummercj states I don't see how this will help with the static analysis tool.

Same with the other assertion please. Though as @plummercj states I don't see how this will help with the static analysis tool.

done.

savoptik · 2025-07-01T07:56:54Z

/summary
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Artem Semenov savoptik@altlinux.org.

openjdk · 2025-07-01T07:58:05Z

@savoptik Setting summary to:

Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Artem Semenov <savoptik@altlinux.org>.

sspitsyn

This looks okay.
However, I agree with David it is not going to address the issue with static analysis tool.
Is it right?
Also, why are there two bugs associated with this PR?

savoptik · 2025-07-01T09:26:59Z

This looks okay. However, I agree with David it is not going to address the issue with static analysis tool. Is it right? Also, why are there two bugs associated with this PR?

Because there are two identical analyzer detections in similar code sections of this file. I created one ticket for each detection. However, I fixed both issues with a single PR.

Regarding the analyzer, we will rerun the analysis with assert enabled and check if it helps to suppress the analyzer warnings

sspitsyn · 2025-07-01T09:45:21Z

Because there are two identical analyzer detections in similar code sections of this file. I created one ticket for each detection. However, I fixed both issues with a single PR.

Is it a specific requirement to create a separate bug for each complain? Normally, one bug for both has to be enough. One bug would be even enough for multiple complains in several files of the same development area.

sspitsyn · 2025-07-01T09:47:02Z

Regarding the analyzer, we will rerun the analysis with assert enabled and check if it helps to suppress the analyzer warnings

Thanks!

savoptik · 2025-07-01T10:11:41Z

Because there are two identical analyzer detections in similar code sections of this file. I created one ticket for each detection. However, I fixed both issues with a single PR.

Is it a specific requirement to create a separate bug for each complain? Normally, one bug for both has to be enough. One bug would be even enough for multiple complains in several files of the same development area.

TNX

sspitsyn · 2025-07-02T11:21:29Z

I'm suggesting to close JDK-8360670 as a dup of JDK-8360664.

savoptik · 2025-07-02T12:07:38Z

I'm suggesting to close JDK-8360670 as a dup of JDK-8360664.

Ok.

savoptik · 2025-07-02T12:49:52Z

/issue remove 8360670

openjdk · 2025-07-02T12:50:06Z

@savoptik
Removing additional issue from issue list: 8360670.

sspitsyn

Looks good. Thank you for closing second bug as a dup.

savoptik · 2025-07-03T07:01:32Z

@alexmenkov @plummercj @dholmes-ora do you mind the integration?

alexmenkov · 2025-07-03T20:18:39Z

I'm fine with the fix, the only question if it helps with the analysis tool.

plummercj · 2025-07-03T20:29:03Z

Same here. I just don't want to see the CR refiled if the analysis tool still complains.

savoptik · 2025-07-07T06:11:02Z

/integrate

openjdk · 2025-07-07T06:11:51Z

Going to push as commit e9a4341.
Since your change was applied there have been 104 commits pushed to the master branch:

45300dd: 8358568: Purge obsolete/broken GenerateSynchronizationCode flag
44cff9d: 8346952: GetGraphicsStressTest.java fails: Native resources unavailable
3bcbcc5: 8361439: [BACKOUT] 8357601: Checked version of JNI ReleaseArrayElements needs to filter out known wrapped arrays
... and 101 more: https://git.openjdk.org/jdk/compare/5039b42de170769797312969185ee9d67f34cf24...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-07-07T06:12:03Z

@savoptik Pushed as commit e9a4341.

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

openjdk bot changed the title ~~8360664 Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object()~~ 8360664: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object() Jun 26, 2025

openjdk bot added the rfr Pull request is ready for review label Jun 26, 2025

openjdk bot added serviceability serviceability-dev@openjdk.org hotspot hotspot-dev@openjdk.org labels Jun 26, 2025

8360664 Null pointer dereference in src/hotspot/share/prims/jvmtiTagM…

e69c49c

…ap.cpp in IterateOverHeapObjectClosure::do_object() Found by Linux Verification Center (linuxtesting.org) with SVACE. signed-off-by: Artem Semenov <savoptik@altlinux.org>

savoptik force-pushed the asemenov/JDK-8360664 branch from ee6a0ff to e69c49c Compare June 26, 2025 13:57

dholmes-ora reviewed Jun 27, 2025

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changed if tu assert

88f1e49

alexmenkov approved these changes Jul 1, 2025

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openjdk bot added the ready Pull request is ready to be integrated label Jul 1, 2025

plummercj approved these changes Jul 1, 2025

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dholmes-ora reviewed Jul 1, 2025

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Updated the text of assert

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openjdk bot removed the ready Pull request is ready to be integrated label Jul 1, 2025

sspitsyn reviewed Jul 1, 2025

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sspitsyn approved these changes Jul 2, 2025

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openjdk bot added the ready Pull request is ready to be integrated label Jul 2, 2025

openjdk bot added the integrated Pull request has been integrated label Jul 7, 2025

openjdk bot closed this Jul 7, 2025

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This was referenced Aug 15, 2025

8365604: Null pointer dereference in src/hotspot/share/adlc/output_h.cpp ArchDesc::declareClasses() #26798

Closed

8365609: Fix several potential NULL native pointer dereferences in the desktop module #26799

Closed

	assert(o != nullptr, "Parameter 'o' must not be null!");
	assert(o != nullptr, "Heap iteration should never produce null");

8360664: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object() #26002

8360664: Null pointer dereference in src/hotspot/share/prims/jvmtiTagMap.cpp in IterateOverHeapObjectClosure::do_object() #26002

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