30dc81f4f5
On traditional 32-bit and 64-bit architectures, uint64_t can be abused
to hold a uintptr_t and be cast back to a valid pointer. However, on
CHERI, and thus Arm's Morello prototype, pointers are capabilities,
which contain a traditional address alongside additional metadata,
including a tag bit that ensures it cannot be forged (the only way to
get a capability with the tag bit set is by using instructions that take
in another valid capability with sufficient bounds/permissions/etc for
the request, and any other operation, like overwriting individual bytes
in memory, will give a capability whose tag is clear). Casting a pointer
to a uintptr_t is fine as uintptr_t is represented as a capability, but
casting to a uint64_t yields just the address, losing the metadata and
tag. Thus, when cast back to a uintptr_t, the capability remains invalid
and faults on any attempt to dereference.
As with various other places in the tree, address this by searching for
the pointer in a list so that we no longer rely on this undefined
behaviour.
Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
(cherry picked from commit
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| damageext | ||
| dbe | ||
| dix | ||
| doc | ||
| dri3 | ||
| fb | ||
| glamor | ||
| glx | ||
| hw | ||
| include | ||
| m4 | ||
| man | ||
| mi | ||
| miext | ||
| os | ||
| present | ||
| randr | ||
| record | ||
| render | ||
| test | ||
| Xext | ||
| xfixes | ||
| Xi | ||
| xkb | ||
| .appveyor.yml | ||
| .dir-locals.el | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| COPYING | ||
| meson.build | ||
| meson_options.txt | ||
| README.md | ||
| xserver.ent.in | ||
X Server
The X server accepts requests from client applications to create windows, which are (normally rectangular) "virtual screens" that the client program can draw into.
Windows are then composed on the actual screen by the X server (or by a separate composite manager) as directed by the window manager, which usually communicates with the user via graphical controls such as buttons and draggable titlebars and borders.
For a comprehensive overview of X Server and X Window System, consult the following article: https://en.wikipedia.org/wiki/X_server
All questions regarding this software should be directed at the Xorg mailing list:
https://lists.freedesktop.org/mailman/listinfo/xorg
The primary development code repository can be found at:
https://gitlab.freedesktop.org/xorg/xserver
For patch submission instructions, see:
https://www.x.org/wiki/Development/Documentation/SubmittingPatches
As with other projects hosted on freedesktop.org, X.Org follows its Code of Conduct, based on the Contributor Covenant. Please conduct yourself in a respectful and civilized manner when using the above mailing lists, bug trackers, etc: