Introduce a settable allocation limit on image loading

[ChangeLog][QtGui][QImageReader] Introduced a settable allocation
limit on image loading to limit resource usage from corrupt image
files.

Change-Id: Ibed7b0cac32798125a060e6db80b17ebc5e70759
Task-number: QTBUG-85037
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/gui/image/qimagereader.cpp b/src/gui/image/qimagereader.cpp
index 684442eb8f..a3ff898222 100644
--- a/src/gui/image/qimagereader.cpp
+++ b/src/gui/image/qimagereader.cpp
@@ -492,8 +492,12 @@ public:
     QString errorString;
 
     QImageReader *q;
+
+    static int maxAlloc;
 };
 
+int QImageReaderPrivate::maxAlloc = 128; // 128 MB is enough for an 8K 32bpp image
+
 /*!
     \internal
 */
@@ -1575,4 +1579,34 @@ QList<QByteArray> QImageReader::imageFormatsForMimeType(const QByteArray &mimeTy
                                                               QImageReaderWriterHelpers::CanRead);
 }
 
+/*!
+    \since 6.0
+
+    Returns the current allocation limit, in megabytes.
+
+    \sa setAllocationLimit()
+*/
+int QImageReader::allocationLimit()
+{
+    return QImageReaderPrivate::maxAlloc;
+}
+
+/*!
+    \since 6.0
+
+    Sets the allocation limit to \a mbLimit megabytes. Images that would
+    require a QImage memory allocation above this limit will be rejected.
+
+    This limit helps applications avoid unexpectedly large memory usage from
+    loading corrupt image files. It is normally not needed to change it. The
+    default limit is large enough for all commonly used image sizes.
+
+    \sa allocationLimit()
+*/
+void QImageReader::setAllocationLimit(int mbLimit)
+{
+    if (mbLimit >= 0)
+        QImageReaderPrivate::maxAlloc = mbLimit;
+}
+
 QT_END_NAMESPACE