Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: fe72eacc753b1a8dbbbb16a71bdb61883bd58cd8
https://github.com/WebKit/WebKit/commit/fe72eacc753b1a8dbbbb16a71bdb61883bd58cd8
Author: Wenson Hsieh <[email protected]>
Date: 2024-01-24 (Wed, 24 Jan 2024)
Changed paths:
M Source/WebKit/UIProcess/ios/WKBaseScrollView.mm
Log Message:
-----------
[iOS] Occasional crash under -_updatePanGestureToPreventScrolling when
resetting state after process termination
https://bugs.webkit.org/show_bug.cgi?id=268011
rdar://121329521
Reviewed by Simon Fraser.
This is a speculative fix for crashes in `-[WKBaseScrollView
_updatePanGestureToPreventScrolling]`
while resetting UI-side state under
`WebPageProxy::resetStateAfterProcessTermination`. From the
crashing stack, this appears to be triggered because:
1. The overflow scroller is being removed from the view hierarchy.
2. UIKit invokes gesture actions one final time, which (after the changes in
271171@main) calls out
to the `ScrollingTreeScrollingNodeDelegateIOS` to ask for active touch
actions for the pan
gesture.
3. The scrolling tree node is already invalid at this point, the
`RemoteScrollingTree` downcast
fails and we crash.
Try to mitigate this by not calling into delegate for locked scrolling axes in
the case where we're
either not in the view hierarchy, or we're in the middle of being removed from
the view hierarchy.
* Source/WebKit/UIProcess/ios/WKBaseScrollView.mm:
(-[WKBaseScrollView removeFromSuperview]):
(-[WKBaseScrollView _axesToPreventScrollingFromDelegate]):
Canonical link: https://commits.webkit.org/273443@main
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