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Check out this insanity: github.com/mozilla/gecko-. The normal choices are a library being extracted to the file system or having it mapped directly from the apk by having it uncompressed. Instead, Firefox uses lazy loading by intercepting segfaults when libraries are used.
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Firefox is beyond hope in terms of hardening due to all the undefined behavior incompatible with mitigations, but in this case they're taking things even further and blocking improvements to the OS. They are literally overwriting a portion of libc with their hard-wired code...
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I love how they even go out of the way to provide their own sigaltstack without a guard page, even though the base system already provides one with a guard page:
github.com/mozilla/gecko-
The code all insanity:
github.com/mozilla/gecko-
It comes up as an issue again and again.
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Oh, and since they load it like this, their code ends up as dirty pages in memory instead of having on-demand paging from shared objects on the filesystem either in the apk (uncompressed) or in the directory of automatically extracted libraries / executables (compressed in apk).
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Transmission of an apk is compressed so having a library uncompressed in the apk like Chromium doesn't waste bandwidth. The apk uses a bit more space on the device, but less than having it both compressed in the apk and extracted alongside it. Firefox's design choice is terrible.
Firefox (fennec) is in semi-maintenance mode -- you should check to see whether Fenix has the same behavior and report it as an issue if so.
github.com/mozilla-mobile
tools.taskcluster.net/index/project.
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