LWN: Comments on "Firefox 76.0"

Firefox 76.0

excors — Wed, 06 May 2020 16:20:35 +0000

Specifically the problem with SharedArrayBuffer is that it can be used as a high-precision timer (per https://blog.mozilla.org/security/2018/01/03/mitigations-...). (One thread can increment a shared value in a loop, and a thread on another CPU core can read it like a clock). Practical Spectre attacks require high-precision timers, so they blocked timers to block the attacks. If attacks were blocked through some other mechanism (like isolating sites) then they could allow SharedArrayBuffer again, at least until the next timing attack is discovered.

Firefox 76.0

Cyberax — Wed, 06 May 2020 15:43:25 +0000

It's a step towards enabling multi-threading for user JavaScript (i.e. SharedArrayBuffer). It has been disabled in 2018 due to Spectre/Meltdown and can't be re-enabled until FireFox learns how to isolate sites from each other.

Firefox 76.0

walters — Wed, 06 May 2020 15:39:08 +0000

That's not multi-threading, it's multi-*processing* right?

Firefox 76.0

flussence — Wed, 06 May 2020 08:30:46 +0000

Undocumented change in this version which makes me *very* happy: throwing a sufficient amount of "revert"s on input/select/textarea in a user stylesheet now restores the native OS widget look if the page changed them.

Firefox 76.0

roc — Tue, 05 May 2020 22:15:52 +0000

There is actually work happening to reenable SharedArrayBuffer+threads independent of Fission. https://groups.google.com/forum/#!msg/mozilla.dev.platfor...

Firefox 76.0

Cyberax — Tue, 05 May 2020 19:51:33 +0000

They're also inching closer to re-enabling the true multi-threading support for JS: https://wiki.mozilla.org/Project_Fission