QNetworkAccessManager: check the buffer size before allocate

The downloadBuffer size should not be larger then the
downloadBufferMaximumSize. I also added a try catch for the allocation
incase we are low on memory, so that we don't crash.

Task-number: QTBUG-23040
Change-Id: Ib9820bc19fc5db994ede20f123f8c167a8d43ff7
Reviewed-by: Peter Hartmann <peter.hartmann@nokia.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/src/network/access/qhttpthreaddelegate.cpp b/src/network/access/qhttpthreaddelegate.cpp
index e03b3fc59d..f0755337fc 100644
--- a/src/network/access/qhttpthreaddelegate.cpp
+++ b/src/network/access/qhttpthreaddelegate.cpp
@@ -472,11 +472,15 @@ void QHttpThreadDelegate::headerChangedSlot()
 
     // Is using a zerocopy buffer allowed by user and possible with this reply?
     if (httpReply->supportsUserProvidedDownloadBuffer()
-        && downloadBufferMaximumSize > 0) {
-        char *buf = new char[httpReply->contentLength()]; // throws if allocation fails
-        if (buf) {
-            downloadBuffer = QSharedPointer<char>(buf, downloadBufferDeleter);
-            httpReply->setUserProvidedDownloadBuffer(buf);
+        && (downloadBufferMaximumSize > 0) && (httpReply->contentLength() <= downloadBufferMaximumSize)) {
+        QT_TRY {
+            char *buf = new char[httpReply->contentLength()]; // throws if allocation fails
+            if (buf) {
+                downloadBuffer = QSharedPointer<char>(buf, downloadBufferDeleter);
+                httpReply->setUserProvidedDownloadBuffer(buf);
+            }
+        } QT_CATCH(const std::bad_alloc &) {
+            // in out of memory situations, don't use downloadbuffer.
         }
     }