Closed Bug 1620347 Opened 3 years ago Closed 5 months ago

Two different full-screen behaviors when privacy.resistFingerprinting.letterboxing = true

Categories

(Core :: DOM: Security, defect, P3)

x86_64
Linux
defect

Tracking

()

RESOLVED DUPLICATE of bug 1450401
Tracking Status
firefox75 --- affected

People

(Reporter: geeknik, Unassigned)

References

Details

(Whiteboard: [fingerprinting][domsecurity-backlog])

Hi. I noticed there are 2 different fullscreen behaviors in Firefox Nightly (ASAN Build ID 20200305095541) on Fedora 31 with xfce4, Nvidia RTX 2070 and v440.64 drivers, but only when you have enabled privacy.resistFingerprinting and privacy.resistFingerprinting.letterboxing.

STR:

  1. Set privacy.resistFingerprinting and privacy.resistFingerprinting.letterboxing to true. Restart as necessary.
  2. Visit YouTube and start playing any video.
  3. Tap F11 on the keyboard.
  4. Notice the letterboxing around the fullscreen video.
  5. Tap F11 to leave full screen, then tap the full screen icon in the YouTube player.
  6. Notice the lack of letterboxing.

YouTube's Stats for nerds reports a viewport of 1477x831 for Theater mode, 1655x931 for F11, and 1920x1080 for YouTube Fullscreen. I'm on a 24" monitor with a native resolution of 1920x1200.

(In reply to Brian Carpenter [:geeknik] from comment #0)

  1. Tap F11 to leave full screen, then tap the full screen icon in the YouTube player.
  2. Notice the lack of letterboxing.

Letterboxing does not apply to elements

Tor: https://trac.torproject.org/projects/tor/ticket/32713

tom: duplicate of bug 1450401 ?


I didn't bother to look at the stats for nerds or how they calculate those values, but 1920x1080 is 16/9 exactly and the other two are as close as possible to 16/9 (whereas your screen is actually 16/10) - so I suspect they're reporting possible video dimensions, not actual viewport/inner/screen measurements

Flags: needinfo?(tom)
Whiteboard: [fingerprint]
Whiteboard: [fingerprint] → [fingerprinting]
Priority: -- → P3
Whiteboard: [fingerprinting] → [fingerprinting][domsecurity-backlog]

Seems pretty close to a dupe, but I'm going to leave it open as something to double check if we get into a position to double check it.

Blocks: letterboxing
Flags: needinfo?(tom)
Status: NEW → RESOLVED
Closed: 5 months ago
Resolution: --- → DUPLICATE
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