When a glibc update accidentally breaks Chromium's audio (2021)
A glibc update in Flatpak runtime 21.08 broke Chromium audio because of a sandbox syscall filter, and the post traces the cause.
Extract
A few weeks ago, I merged in a pull request to update the Chromium Flatpak to use runtime version 21.08. I had given it some testing without running into any issues, plus the binary-compiled Chromium variants like Chrome, Brave, and Edge were all already on runtime 21.08, thus it seemed like an easy merge. What could go wrong? Then, the next morning, I woke up to see a PR filed to revert the change, due to a newly filed issue detailing that the update broke video playback, with some errors about the "audio renderer". So, it turns out, a lot could go wrong. First off, I tried it out myself and confirmed that YouTube was completely broken. This didn’t show up in testing because I almost never use YouTube on desktop, preferring the mobile app instead, so I failed to observe any issues with it. The logs in the issue were interesting: Oct 05 09:51:57 fedora org.chromium.Chromium.desktop[2865]: [2:19:1005/095157.560929:ERROR:chrome_browser_main_extra_parts_metrics.cc(228)] crbug.com/1216328: Checking Bluetooth availability started. Please report if there is no report that this ends. Oct 05 09:51:57 fedora org.chromium.Chromium.desktop[2865]: [2:19:1005/095157.560954:ERROR:chrome_browser_main_extra_parts_metrics.cc(231)] crbug.com/1216328: Checking Bluetooth availability ended. Oct 05 09:51:57 fedora org.chromium.Chromium.desktop[2865]: [2:19:1005/095157.560962:ERROR:chrome_browser_main_extra_parts_metrics.cc(234)] crbug.com/1216328: Checking default browser status started. Please report if there is no report that this ends. Oct 05 09:51:57 fedora org.chromium.Chromium.desktop[2865]: [2:19:1005/095157.567208:ERROR:chrome_browser_main_extra_parts_metrics.cc(238)] crbug.com/1216328: Checking default browser status ended. Oct 05 09:52:16 fedora org.chromium.Chromium.desktop[3529]: The futex facility returned an unexpected error code. Oct 05 09:52:16 fedora org.chromium.Chromium.desktop[3543]: Failed to load cookie file from cookie: Permission denied Oct 05 09:52:16 fedora org.chromium.Chromium.desktop[3543]: The futex facility returned an unexpected error code. Oct 05 09:52:17 fedora org.chromium.Chromium.desktop[3648]: Failed to load cookie file from cookie: Permission denied Oct 05 09:52:17 fedora org.chromium.Chromium.desktop[3648]: The futex facility returned an unexpected error code. The last several lines are definitely not from Chromium itself, as they don’t follow the standard Chromium log format. A quick google of the error pointed me to this Gentoo issue, …