Check on CFStringRef type before of QString creation

It is make sense to check the returned QCFType<CFTypeRef> property on
the null-pointer and on the CFStringRef type to exclude of possible
exception.

Thanks to Orest Hera.

(cherry-picked from bc948f5f695908ad11a19b1336975d07ff1de0e1)
Change-Id: I09f784b9ce8aa471dfb53181798d0066945efc86
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/serialport/qserialportinfo_mac.cpp b/src/serialport/qserialportinfo_mac.cpp
index 3f242f1..a07db06 100644
--- a/src/serialport/qserialportinfo_mac.cpp
+++ b/src/serialport/qserialportinfo_mac.cpp
@@ -72,7 +72,11 @@ static QCFType<CFTypeRef> searchProperty(io_registry_entry_t ioRegistryEntry,
 static QString searchStringProperty(io_registry_entry_t ioRegistryEntry,
                                     const QCFString &propertyKey)
 {
-    return QCFString::toQString(searchProperty(ioRegistryEntry, propertyKey).as<CFStringRef>());
+    const QCFType<CFTypeRef> result(searchProperty(ioRegistryEntry, propertyKey));
+    const CFStringRef ref = result.as<CFStringRef>();
+    if (ref && (::CFGetTypeID(ref) == ::CFStringGetTypeID()))
+        return QCFString::toQString(ref);
+    return QString();
 }
 
 static quint16 searchShortIntProperty(io_registry_entry_t ioRegistryEntry,