qdoc: Fix heap-use-after-free and memory leak issues

Some of the created nodes appear multiple times in QDoc's node tree.
This caused issues with address sanitizer during deletion of the
tree: Nodes were checked for their parent() node, and the parent
node might have been deleted already.

Implement a cleanup function that removes all children that do not
report *this* node as their parent from the list of children -
after this, the tree can be safely deleted by destroying the root
node.

Fix memory leak issues; a couple of potential leaks in
ClangCodeParser caused by not freeing resources in all cases,
and DocBookGenerator leaking a QFile instance per each generated
file.

Pick-to: 6.2
Fixes: QTBUG-97627
Change-Id: If279b55ee24dc1b7291951ef11b7a26276df167c
Reviewed-by: Luca Di Sera <luca.disera@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/qdoc/clangcodeparser.cpp b/src/qdoc/clangcodeparser.cpp
index d61b24270..1b9096e97 100644
--- a/src/qdoc/clangcodeparser.cpp
+++ b/src/qdoc/clangcodeparser.cpp
@@ -1392,11 +1392,11 @@ void ClangCodeParser::buildPCH()
                     visitor.visitChildren(cur);
                     qCDebug(lcQdoc) << "PCH built and visited for" << moduleHeader();
                 }
-                clang_disposeTranslationUnit(tu);
             } else {
                 m_pchFileDir->remove();
                 qCCritical(lcQdoc) << "Could not create PCH file for " << moduleHeader();
             }
+            clang_disposeTranslationUnit(tu);
             m_args.pop_back(); // remove the "-xc++";
         }
     }
@@ -1470,6 +1470,7 @@ void ClangCodeParser::parseSourceFile(const Location & /*location*/, const QStri
 
     if (err || !tu) {
         qWarning() << "(qdoc) Could not parse source file" << filePath << " error code:" << err;
+        clang_disposeTranslationUnit(tu);
         clang_disposeIndex(index_);
         return;
     }
@@ -1715,6 +1716,7 @@ void ClangCodeParser::printDiagnostics(const CXTranslationUnit &translationUnit)
         auto formattedDiagnostic = clang_formatDiagnostic(diagnostic, displayOptions);
         qCDebug(lcQdocClang) << clang_getCString(formattedDiagnostic);
         clang_disposeString(formattedDiagnostic);
+        clang_disposeDiagnostic(diagnostic);
     }
 }