Title: [283209] trunk/Source/WebKit
- Revision
- 283209
- Author
- [email protected]
- Date
- 2021-09-28 20:52:14 -0700 (Tue, 28 Sep 2021)
Log Message
Crash in WebKit::DisplayLink::displayLinkCallback()
https://bugs.webkit.org/show_bug.cgi?id=230917
<rdar://82528370>
Reviewed by Tim Horton.
We have evidence of a divide-by-zero crash in DisplayLink::notifyObserversDisplayWasRefreshed()
where m_currentUpdate.updatesPerSecond is zero. The only way I can see this happening
is if DisplayLink::DisplayLink() returns early, which should log. Protect against
this by initializing m_displayNominalFramesPerSecond to 60, and do another check,
with a log, in DisplayLink::addObserver() before we use m_displayNominalFramesPerSecond
for the first time.
Convert the logging to RELEASE_LOG_FAULT reports.
* UIProcess/mac/DisplayLink.cpp:
(WebKit::DisplayLink::DisplayLink):
(WebKit::DisplayLink::addObserver):
* UIProcess/mac/DisplayLink.h:
Modified Paths
Diff
Modified: trunk/Source/WebKit/ChangeLog (283208 => 283209)
--- trunk/Source/WebKit/ChangeLog 2021-09-29 03:16:47 UTC (rev 283208)
+++ trunk/Source/WebKit/ChangeLog 2021-09-29 03:52:14 UTC (rev 283209)
@@ -1,3 +1,25 @@
+2021-09-28 Simon Fraser <[email protected]>
+
+ Crash in WebKit::DisplayLink::displayLinkCallback()
+ https://bugs.webkit.org/show_bug.cgi?id=230917
+ <rdar://82528370>
+
+ Reviewed by Tim Horton.
+
+ We have evidence of a divide-by-zero crash in DisplayLink::notifyObserversDisplayWasRefreshed()
+ where m_currentUpdate.updatesPerSecond is zero. The only way I can see this happening
+ is if DisplayLink::DisplayLink() returns early, which should log. Protect against
+ this by initializing m_displayNominalFramesPerSecond to 60, and do another check,
+ with a log, in DisplayLink::addObserver() before we use m_displayNominalFramesPerSecond
+ for the first time.
+
+ Convert the logging to RELEASE_LOG_FAULT reports.
+
+ * UIProcess/mac/DisplayLink.cpp:
+ (WebKit::DisplayLink::DisplayLink):
+ (WebKit::DisplayLink::addObserver):
+ * UIProcess/mac/DisplayLink.h:
+
2021-09-28 Brent Fulgham <[email protected]>
Remove unused "com.apple.security.exception.file*" rules from WebKit sandboxes
Modified: trunk/Source/WebKit/UIProcess/mac/DisplayLink.cpp (283208 => 283209)
--- trunk/Source/WebKit/UIProcess/mac/DisplayLink.cpp 2021-09-29 03:16:47 UTC (rev 283208)
+++ trunk/Source/WebKit/UIProcess/mac/DisplayLink.cpp 2021-09-29 03:52:14 UTC (rev 283209)
@@ -48,13 +48,13 @@
ASSERT(hasProcessPrivilege(ProcessPrivilege::CanCommunicateWithWindowServer));
CVReturn error = CVDisplayLinkCreateWithCGDisplay(displayID, &m_displayLink);
if (error) {
- WTFLogAlways("Could not create a display link for display %u: error %d", displayID, error);
+ RELEASE_LOG_FAULT(DisplayLink, "Could not create a display link for display %u: error %d", displayID, error);
return;
}
error = CVDisplayLinkSetOutputCallback(m_displayLink, displayLinkCallback, this);
if (error) {
- WTFLogAlways("Could not set the display link output callback for display %u: error %d", displayID, error);
+ RELEASE_LOG_FAULT(DisplayLink, "DisplayLink: Could not set the display link output callback for display %u: error %d", displayID, error);
return;
}
@@ -103,8 +103,13 @@
LOG_WITH_STREAM(DisplayLink, stream << "[UI ] DisplayLink for display " << m_displayID << " starting CVDisplayLink with fps " << m_displayNominalFramesPerSecond);
CVReturn error = CVDisplayLinkStart(m_displayLink);
if (error)
- WTFLogAlways("Could not start the display link: %d", error);
+ RELEASE_LOG_FAULT(DisplayLink, "DisplayLink: Could not start the display link: %d", error);
+ if (!m_displayNominalFramesPerSecond) {
+ RELEASE_LOG_FAULT(DisplayLink, "DisplayLink: displayNominalFramesPerSecond is 0, using %d", WebCore::FullSpeedFramesPerSecond);
+ m_displayNominalFramesPerSecond = WebCore::FullSpeedFramesPerSecond;
+ };
+
m_currentUpdate = { 0, m_displayNominalFramesPerSecond };
}
}
Modified: trunk/Source/WebKit/UIProcess/mac/DisplayLink.h (283208 => 283209)
--- trunk/Source/WebKit/UIProcess/mac/DisplayLink.h 2021-09-29 03:16:47 UTC (rev 283208)
+++ trunk/Source/WebKit/UIProcess/mac/DisplayLink.h 2021-09-29 03:52:14 UTC (rev 283209)
@@ -87,7 +87,7 @@
Lock m_observersLock;
HashMap<IPC::Connection::UniqueID, ConnectionClientInfo> m_observers WTF_GUARDED_BY_LOCK(m_observersLock);
WebCore::PlatformDisplayID m_displayID;
- WebCore::FramesPerSecond m_displayNominalFramesPerSecond { 0 };
+ WebCore::FramesPerSecond m_displayNominalFramesPerSecond { WebCore::FullSpeedFramesPerSecond };
WebCore::DisplayUpdate m_currentUpdate;
unsigned m_fireCountWithoutObservers { 0 };
static bool shouldSendIPCOnBackgroundQueue;
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