Bug 439492

Summary:	TextCreator::create() crashes in QSyntaxHighligher.
Product:	[Frameworks and Libraries] kio-extras	Reporter:	RJVB <rjvbertin>
Component:	Thumbnails and previews	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	crash	CC:	christoph
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Compiled Sources
OS:	All
See Also:	https://bugs.kde.org/show_bug.cgi?id=439491
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Bug Depends on:	439491
Bug Blocks:

Description RJVB 2021-07-04 19:53:33 UTC

SUMMARY
TextCreator::create() creates a locate instance using `KSyntaxHighlighting::SyntaxHighlighter syntaxHighlighter;` which leads to a nullptr dereference in `QSyntaxHighlighter::QSyntaxHighlighter(QObject*)`.

STEPS TO REPRODUCE
1. Open a directory in Dolphin, activate hover-on previews
2. Hover the cursor over a .txt file

OBSERVED RESULT
kdeinit5 crashes because of the nullptr dereference.

EXPECTED RESULT
No crash.

SOFTWARE/OS VERSIONS
Happens on Mac & Linux; as far as I can tell this should happen with the current Qt5 release and the most recent versions of kio-extras and KSyntaxHighlighting.

ADDITIONAL INFORMATION
The function should call `KSyntaxHighlighting::SyntaxHighlighter syntaxHighlighter(&textDocument);` which makes the later call to `setDocument()` unnecessary.

Comment 1 Christoph Cullmann 2021-07-04 19:55:13 UTC

Hmm, all At versions we support should have the null check, we submitted that ourselves

https://code.qt.io/cgit/qt/qtbase.git/commit/src/gui/text/qsyntaxhighlighter.cpp?id=16cb578a8d102f1c937dcc3a07b88b24c9ed685a

Comment 2 RJVB 2021-07-04 20:39:50 UTC

(You could have "unprivatised" the argument-less ctor or added a default null value in the fix ;) )