1793906 - Assertion failure: sideBits == hit.mNode->GetFixedPosSides() (Fixed position side bits do not match), at WRHitTester.cpp:230

Status: NEW

(Core :: Panning and Zooming, defect, P2)

Description

[Gabriele Svelto [:gsvelto]]

I was doing some testing in a debug build and Firefox crashed twice hitting this assertion:

[Child 31410, Main Thread] WARNING: '!CanHandleWith(aPresContext)', file /home/gsvelto/projects/mozilla-central/dom/events/IMEStateManager.cpp:499
Assertion failure: sideBits == hit.mNode->GetFixedPosSides() (Fixed position side bits do not match), at /home/gsvelto/projects/mozilla-central/gfx/layers/apz/src/WRHitTester.cpp:229

This was on Linux. My STR is rather simple:

• Browse to https://www.cnn.com
• Disable tracking protection so that plenty of ad frames load
• Scroll around, open articles and scroll around some more, eventually I hit the assertion
• A couple of times I didn't hit it while scrolling but rather right when I closed Firefox

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1778120

:dlrobertson, since you are the author of the regressor, bug 1778120, could you take a look?

For more information, please visit auto_nag documentation.

Comment 2

[Botond Ballo [:botond]]

Since we have a reduced testcase in bug 1792830, it makes sense to investigate that one first, and then re-test the STR in this bug once that one is fixed.

Comment 3

[Donal Meehan [:dmeehan]]

Setting 107 to disabled, regressor Bug 1778120 was backed out of central.

Comment 4

[:gerard-majax]

According to https://bugzilla.mozilla.org/show_bug.cgi?id=1835231#c22 it still repros on Android?

Comment 5

[Botond Ballo [:botond]]

(In reply to Alexandre LISSY :gerard-majax from comment #4)

According to https://bugzilla.mozilla.org/show_bug.cgi?id=1835231#c22 it still repros on Android?

Looks like it, yeah. That would be a regression from bug 1753019, which originally added the assertion on Android.

Comment 6

[Botond Ballo [:botond]]

Going to bump this to a P2. While I can't reproduce the instance of this assertion linked to in comment 4, it suggests that the underlying issue may be affecting platforms where the affected code is enabled (i.e. Android), not just desktop where it's disabled.

Comment 7

[Chris Peterson [:cpeterson]]

I reliably hit this "Fixed position side bits do not match" assertion failure:

https://searchfox.org/mozilla-central/rev/6d437ba43e7752a85f5731133ee66152b390aa16/gfx/layers/apz/src/WRHitTester.cpp#226-230

in a debug GeckoViewExample build (128.0a1) when trying to scroll up and down the following page in the Android emulator:

https://www.samsung.com/us/smartphones/galaxy-s23-ultra/