Check for integer overflows in places where qAllocMore is used

Task-number: QTBUG-41230
Change-Id: I5e932c2540c0bd67f13fab3ae20975d459f82c08
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/corelib/tools/qtools_p.h b/src/corelib/tools/qtools_p.h
index 3876d3822c..1e72db1d87 100644
--- a/src/corelib/tools/qtools_p.h
+++ b/src/corelib/tools/qtools_p.h
@@ -46,9 +46,15 @@
 //
 
 #include "QtCore/qglobal.h"
+#include <limits>
 
 QT_BEGIN_NAMESPACE
 
+// We typically need an extra bit for qNextPowerOfTwo when determining the next allocation size.
+enum {
+    MaxAllocSize = (1 << (std::numeric_limits<int>::digits - 1)) - 1
+};
+
 // implemented in qbytearray.cpp
 int Q_CORE_EXPORT qAllocMore(int alloc, int extra) Q_DECL_NOTHROW;