Fedora 38 To Prohibit Byte Swapped Xorg and Xwayland Clients

slack_justyb writes: A rather exotic feature in Xorg and Xwayland is being proposed to have the default value turned off going forward in Fedora 38 due to its use in attacks (CVE-2014-8095, CVE-2014-8099, CVE-2014-8103. . . to name a few). The feature allows servers running on one endianess to byte-swap to allow clients of a different endianess to connect to it. This was more common in the 1980s when X servers ran on big-endian and clients would connect who were little-endian. The Xorg and Xwayland implementation of this feature has gone largely untested, the number of Fedora users that use it are virtually zero, and considering the number of attack vectors this has presented historically, setting the default to deny clients that require this seems the better way to do. This change will be to the xorg-x11-server and xorg-x11-server-Xwayland packages and those needing the feature turned back will need to add "AllowSwappedClients" "on" to their xorg.conf.d file in the "ServerFlags" section. Xwayland users will need to pass the +byteswappedclients flag, however, the compositor will need to be able to handle this flag which at this time GNOME does not.

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