1848891 - Firefox displays page with some missing characters

Status: UNCONFIRMED

(Core :: Graphics: Text, defect)

Description

[Vincent Lefevre]

Attachment: missing-chars.png

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/116.0

Steps to reproduce:

Open https://fr.wikipedia.org/wiki/Un_coup_de_ma%C3%AEtre

Actual results:

In the infobox, some characters were missing (only "a" and "u", but not all of the occurrences of these 2 letters). See attached screenshot.

Expected results:

All the characters should have been displayed.

Selecting the text made the characters appear.

AFAIK, this is the first time I have such an issue (with any application), and I don't know how to reproduce it.

This occurred with Debian's package firefox 116.0-2 (which uses Debian's libraries).

Possibly related: bug 906789 (there are other bugs about missing characters, but apparently not for Linux).

Comment 1

[Vincent Lefevre]

The problem appeared again, with much more missing characters, this time on the IMDb. So this really seems to be a new bug.

Comment 2

[Darkspirit]

Please open about:support, click on "Copy text to clipboard" and paste it here. Thanks!

Comment 3

[Vincent Lefevre]

Attachment: about:support contents

Comment 4

[Bob Hood [:bhood]]

Jonathan, are there any insights you might be able to provide here?

Comment 5

[Jonathan Kew [:jfkthame]]

This looks to me like some kind of graphics-driver-level problem, where blitting the rasterized glyphs is sometimes failing.

The text has clearly been shaped successfully by the content process; the glyphs are in the right places. And the rendering process is successfully rasterizing them; it's not a case where every instance of a given glyph is missing. But sometimes they're failing to finally get painted.

One interesting thing is the missing glyph in "Anaïde Roz_m" (should be "Anaïde Rozam"): looking closely, we can see that a sliver of the missing "a" is actually visible at the bottom edge. So there's no question that the glyph "is there", from Gecko's point of view, and has been rasterized; the failure is somewhere late in the painting pipeline; maybe in webrender or further down in graphics card driver?

Passing ni? on to Lee for further thoughts....

Comment 6

[Lee Salzman [:lsalzman]]

Generally when we see these kind of bugs, especially when they are not readily reproducible, this tends to be some form of graphics driver bug or corruption, not uncommon with a lot of Mesa drivers. If this becomes a larger trend we can spend more time investigating, but for now this might not be actionable.

If you can post your "about:support" contents we can take a look and see if it's a GPU/driver with known or suspected issues.

Comment 7

[Vincent Lefevre]

(In reply to Lee Salzman [:lsalzman] from comment #6)

If you can post your "about:support" contents we can take a look and see if it's a GPU/driver with known or suspected issues.

I've already posted my about:support contents: see comment #3 and attachments.