Changeset 280653 in webkit

Timestamp:

Aug 4, 2021, 1:20:52 PM (5 years ago)

Author:

Simon Fraser

Message:

Crash in DisplayLink::notifyObserversDisplayWasRefreshed() on macOS
​https://bugs.webkit.org/show_bug.cgi?id=228790
<rdar://81338621>

Reviewed by Tim Horton.

Defend against DisplayLink::nominalFramesPerSecondFromDisplayLink() returning zero,
which can result in a later divide by zero in m_currentUpdate.nextUpdate().

• UIProcess/mac/DisplayLink.cpp:

(WebKit::DisplayLink::nominalFramesPerSecondFromDisplayLink):

Location:

trunk/Source/WebKit

Files:

• ChangeLog (modified) (1 diff)
• UIProcess/mac/DisplayLink.cpp (modified) (1 diff)

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2021-08-04  Simon Fraser  <simon.fraser@apple.com>
+
+        Crash in DisplayLink::notifyObserversDisplayWasRefreshed() on macOS
+        https://bugs.webkit.org/show_bug.cgi?id=228790
+        <rdar://81338621>
+
+        Reviewed by Tim Horton.
+
+        Defend against DisplayLink::nominalFramesPerSecondFromDisplayLink() returning zero,
+        which can result in a later divide by zero in m_currentUpdate.nextUpdate().
+
+        * UIProcess/mac/DisplayLink.cpp:
+        (WebKit::DisplayLink::nominalFramesPerSecondFromDisplayLink):
+
 2021-08-04  Said Abou-Hallawa  <said@apple.com>
 

trunk/Source/WebKit/UIProcess/mac/DisplayLink.cpp

@@ -80 +80 @@
 {
     CVTime refreshPeriod = CVDisplayLinkGetNominalOutputVideoRefreshPeriod(displayLink);
-    return round((double)refreshPeriod.timeScale / (double)refreshPeriod.timeValue);
+    if (!refreshPeriod.timeValue)
+        return WebCore::FullSpeedFramesPerSecond;
+
+    WebCore::FramesPerSecond result = round((double)refreshPeriod.timeScale / (double)refreshPeriod.timeValue);
+    return result ?: WebCore::FullSpeedFramesPerSecond;
 }