Schannel: Return if socket is invalid

In a couple places we already check if the socket is connected,
however we can be connected _and_ have the socket be closed.
The logic behind that I don't really understand, but there are
similar checks for validity in the OpenSSL backend.

This happens when calling close() on a still-connecting
socket. The QIODevice is marked as closed, but the connection
cannot yet be aborted. And when it finishes connecting we
handle the signal, start encryption, and then disconnect.

Pick-to: 6.6 6.5
Fixes: QTBUG-116550
Change-Id: I06c0a2db32bea0b573a99a971b8fb0b66a7a73d5
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/plugins/tls/schannel/qtls_schannel.cpp b/src/plugins/tls/schannel/qtls_schannel.cpp
index 728e885029..98856288d4 100644
--- a/src/plugins/tls/schannel/qtls_schannel.cpp
+++ b/src/plugins/tls/schannel/qtls_schannel.cpp
@@ -1023,6 +1023,8 @@ bool TlsCryptographSchannel::sendToken(void *token, unsigned long tokenLength, b
     Q_ASSERT(d);
     auto *plainSocket = d->plainTcpSocket();
     Q_ASSERT(plainSocket);
+    if (plainSocket->state() == QAbstractSocket::UnconnectedState || !plainSocket->isValid())
+        return false;
 
     const qint64 written = plainSocket->write(static_cast<const char *>(token), tokenLength);
     if (written != qint64(tokenLength)) {
@@ -1385,7 +1387,7 @@ bool TlsCryptographSchannel::performHandshake()
     auto *plainSocket = d->plainTcpSocket();
     Q_ASSERT(plainSocket);
 
-    if (plainSocket->state() == QAbstractSocket::UnconnectedState) {
+    if (plainSocket->state() == QAbstractSocket::UnconnectedState || !plainSocket->isValid()) {
         setErrorAndEmit(d, QAbstractSocket::RemoteHostClosedError,
                         QSslSocket::tr("The TLS/SSL connection has been closed"));
         return false;
@@ -1761,7 +1763,7 @@ void TlsCryptographSchannel::transmit()
         return; // This function should not have been called
 
     // Can happen if called through QSslSocket::abort->QSslSocket::close->QSslSocket::flush->here
-    if (plainSocket->state() == QAbstractSocket::SocketState::UnconnectedState)
+    if (plainSocket->state() == QAbstractSocket::UnconnectedState || !plainSocket->isValid())
         return;
 
     if (schannelState != SchannelState::Done) {