Fix potential division by zero.

In a Chrome Remote Desktop session the htotal and/or vtotal timings
can be zero and lead to a SIGFPE exception.

Task-number: QTBUG-49322
Change-Id: Id530335cc760d1938ed888ad095427fcf32c651d
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Nicolas Capens <nicolas.capens@gmail.com>
Reviewed-by: Gatis Paeglis <gatis.paeglis@theqtcompany.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index 2a53b18890..0e99d58679 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -558,7 +558,8 @@ void QXcbScreen::updateRefreshRate(xcb_randr_mode_t mode)
         for (; modesIter.rem; xcb_randr_mode_info_next(&modesIter)) {
             xcb_randr_mode_info_t *modeInfo = modesIter.data;
             if (modeInfo->id == mode) {
-                m_refreshRate = modeInfo->dot_clock / (modeInfo->htotal * modeInfo->vtotal);
+                const uint32_t dotCount = modeInfo->htotal * modeInfo->vtotal;
+                m_refreshRate = (dotCount != 0) ? modeInfo->dot_clock / dotCount : 0;
                 m_mode = mode;
                 break;
             }