Bug 278187 – REGRESSION(278818@main): Crash in Epiphany when closing a tab before gesture completes

• Component: WebKitGTK
• Status: NEW

[darkblaze69]

Created attachment 472182 [details]
gdb.log

* Epiphany version: 47.beta-30-g8f6b6395d
* WebKitGTK version: 2.45.6
* Distributor: Arch Linux

Crash when closing a tab.

[Michael Catanzaro]

So the problem here is:

 * Gesture begins
 * Tab is closed, web view is destroyed
 * Gesture finishes, WebPageProxy::didEndViewGesture calls WebPageProxy::protectedPageClient
 * PageClient::ref attempts to g_object_ref() the destroyed web view
 * object_ref: assertion '!object_already_finalized' failed

[Michael Catanzaro]

Any chance you're able to reproduce this? (Probably not, but if so, that would make this easier....)

[Michael Catanzaro]

Some thoughts:

 * PageClientImpl really needs to hold a GWeakPtr to the WebKitWebView, rather than a raw pointer
 * Separately, there's likely an error somewhere in ViewGestureController or the related code. The gesture should keep things alive if necessary.

[darkblaze69]

I don't have a way to reproduce the crash yet, but had a crash again today. Looks similar. I will add the new gdb log.

[darkblaze69]

Created attachment 472198 [details]
gdb-142753.log

[darkblaze69]

I found a way to reproduce the crash.

1. do the back gesture and keep holding 2 fingers (don't finish the gesture)
2. ctrl-w to close the tab

[darkblaze69]

Looks like regression in 2.45. In 2.44 it just closes the tab.

[darkblaze69]

2.45.2 is good
2.45.3 is bad

Bisected to [d74204522d48951c10bb31282e991ce3a7df96d7] [macOS] Add a mechanism to temporarily suppress text indicators during scrolling/resizing/zooming.

Though it's for macOS. But previous commit 9a38b690ee9a is good and it proves the bisection.

[Michael Catanzaro]

Thanks. That helps.

[Michael Catanzaro]

Ultimately I think this is a bug in WebPageProxy. m_pageClient is a WeakPtr, but WebPageProxy::protectedPageClient allows converting to a Ref without checking whether it's valid. Using WebPageProxy::optionalProtectedPageClient would avoid this. Surely WebPageProxy::protectedPageClient should be removed, but that's going to be annoying to change.