8373475: Unintentional format string in logString of AccessInfo.cpp #28950

DamonGuy · 2025-12-22T05:30:11Z

This update is to fix the potential issue where tmpbuf can be read as a format argument for fprintf. I have added a specifier here to avoid this issue since the string from tmpbuf is not guaranteed to not cause issues. This update should make this print more reliable and safe to use.

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Issue

JDK-8373475: Unintentional format string in logString of AccessInfo.cpp (Bug - P3)

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Alexander Zvegintsev (@azvegint - Reviewer) Review applies to 7ff146b4
Alexey Ivanov (@aivanov-jdk - Reviewer)
Phil Race (@prrace - Reviewer)

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$ git pull https://git.openjdk.org/jdk.git pull/28950/head

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$ git pr checkout 28950

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bridgekeeper · 2025-12-22T05:31:16Z

👋 Welcome back dnguyen! 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 · 2025-12-22T05:31:44Z

@DamonGuy 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:

8373475: Unintentional format string in logString of AccessInfo.cpp

Reviewed-by: aivanov, prr, azvegint

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 131 new commits pushed to the master branch:

61cb6d7: 8374232: Comment cleanup in diagnosticCommand.cpp
8d80bac: 8374296: Comment clean up in os_linux.cpp
be2ac08: 8373967: [macos] User interactions with List do not trigger ItemEvent after programmatic change
... and 128 more: https://git.openjdk.org/jdk/compare/b6319f5b42738cc760711a3b8b5d442d14a0ed74...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 · 2025-12-22T05:32:25Z

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

client

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

mlbridge · 2025-12-22T05:36:54Z

Webrevs

src/jdk.accessibility/windows/native/toolscommon/AccessInfo.cpp

aivanov-jdk · 2025-12-23T17:22:08Z

src/jdk.accessibility/windows/native/toolscommon/AccessInfo.cpp


-    fprintf(logfile, tmpbuf);
-    fprintf(logfile, "\n");
+    fprintf(logfile, "%s\n", tmpbuf);


Why can't we use fputs and avoid all the format string logic and ambiguity altogether?

Alternatively, use vfprintf directly instead of first formatting the arguments into a temporary buffer with vsnprintf and then sending the result to the output.

A similar pattern is used elsewhere in this file. And I don't want this fix to become a reworking of this code, because that isn't a goal here.

After reading about fputs, I think this is best. Like you mentioned, no ambiguity since it does not use specifiers. Updated.

A similar pattern is used elsewhere in this file. And I don't want this fix to become a reworking of this code, because that isn't a goal here.

Indeed, it is.

I agree it's better to keep the code consistent.

At the same time, I think it's worth submitting a bug to simplify usages like that, fputs works perfectly for strings that don't require formatting.

Since Damon already made the change and its just one line I'm fine to keep it but not go looking for more.

src/jdk.accessibility/windows/native/toolscommon/AccessInfo.cpp

prrace · 2025-12-23T19:54:41Z

src/jdk.accessibility/windows/native/toolscommon/AccessInfo.cpp


-    fprintf(logfile, tmpbuf);
-    fprintf(logfile, "\n");
+    fprintf(logfile, "%s\n", tmpbuf);


A similar pattern is used elsewhere in this file. And I don't want this fix to become a reworking of this code, because that isn't a goal here.

prrace

wait where's the \n gone ?

aivanov-jdk · 2025-12-23T20:23:48Z

src/jdk.accessibility/windows/native/toolscommon/AccessInfo.cpp


-    fprintf(logfile, tmpbuf);
-    fprintf(logfile, "\n");
+    fputs(tmpbuf, logfile);


Since fputs doesn't add a line break automatically, you have to add it explicitly.

fputs(tmpbuf, logfile); fputs("\n", logfile);

Thanks for catching this too!

prrace · 2025-12-23T20:26:53Z

src/jdk.accessibility/windows/native/toolscommon/AccessInfo.cpp


-    fprintf(logfile, tmpbuf);
-    fprintf(logfile, "\n");
+    fputs(tmpbuf, logfile);


unless I'm missing something you'd need to add a 2nd fputs for the newline or go back to fprintf like before the latest comment.

I have gone back to fprintf for consistency as you mentioned above. Newline is included. Thanks!

DamonGuy · 2025-12-24T00:03:16Z

/integrate

openjdk · 2025-12-24T00:05:28Z

Going to push as commit a59dbc5.
Since your change was applied there have been 133 commits pushed to the master branch:

72e1e15: 8373474: 2 Unintentional format string defect groups in jabswitch.cpp
f5249db: 8374233: Overloaded constructor MountUnmountDisabler(jthread thread) is missed
61cb6d7: 8374232: Comment cleanup in diagnosticCommand.cpp
... and 130 more: https://git.openjdk.org/jdk/compare/b6319f5b42738cc760711a3b8b5d442d14a0ed74...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-12-24T00:05:36Z

@DamonGuy Pushed as commit a59dbc5.

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

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fputs and copyright

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8373474: 2 Unintentional format string defect groups in jabswitch.cpp #28949

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8373475: Unintentional format string in logString of AccessInfo.cpp #28950

8373475: Unintentional format string in logString of AccessInfo.cpp #28950

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