1802798 - WebAudio crashing on CPUs without DAZ mode

Status: RESOLVED FIXED

(Core :: Web Audio, defect)

Description

[Karo Gyoker]

Steps to reproduce:

• Firefox crashes on Linux if user tries to open the Windows 10 ISO download page 1 on a CPU without DAZ mode
• The Windows 10 ISO download page is utilizing WebAudio when doing browser fingerprinting
• In DenormalDisabler.h it is not being checked correctly if the CPU supports DAZ mode or not
• The bug is originally found in Debian on Athlon XP 2
• The bug is in Firefox upstream too
• The bug was in WebKit as well, but it got fixed (by me) 3
• Firefox 107.0's hardware requirement is Pentium 4 or newer processor that supports SSE2 4
• Not all Penitum 4 CPUs support the DAZ bit: "The processor must support DAZ mode. Initial steppings of Pentium® 4 processors did not support DAZ." 5
• Pentium 4 on Linux is a Tier-1 Target 6
• Blink upstream is not affected since SSE3 is a requirement 7 and every SSE3 capable CPU support DAZ mode
• Windows is not affected since all the supported x86 CPUs 8 support DAZ mode
• Therefore the bug is only reproducible on Linux running on an "inital stepping of Pentium 4" 9
• I haven't found any exact information which steppings are affected, but I don't have a Pentium 4 anyways
• I cannot rebuild Firefox for 32 bit target as the instructions 10 are not working anymore
• I can rebuild firefox-esr though for Debian by using sbuild -v --arch=i386 -d bullseye firefox-esr
• A workaround is to set dom.webaudio.enabled to false in about:config

Actual results:

Tab crashed

Expected results:

Display Windows 10 ISO download page

Comment 1

[Karo Gyoker]

Attachment: Bug 1802798 - Fix WebAudio crash on x86_32 CPUs without DAZ mode. r?dminor

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2e8249668e13
Fix WebAudio crash on x86_32 CPUs without DAZ mode. r=padenot

Comment 3

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/2e8249668e13