As of currently, when an xcursor theme depends on itself or another theme
that will eventually depend on it, `xcursor_load_theme` will recurse
infinitely while processing the inherits.
This change introduces a stack-allocated linked list of visited nodes
by name, and skips any already visited nodes in the inherit list.
Side effects:
* Since the linked list is stack-allocated, there is a potential for an
overflow if there is a very long list of dependencies. If this turns out
to be a legitimate concern, the linked list is trivial to convert to
being heap-allocated.
* There is an existing linked list (technically doubly linked list)
implementation in the wayland codebase. As of currently, the xcursor
codebase does not refer to it. Consequently, this change writes a
minimal single linked list implementation to utilize directly.
This changeset is based on the merge request in wayland/wayland!376.
The xcursor code is mostly shared between the two.
This changeset diverges the files slightly due to stylistic differences
between the repositories, but the logic is identical.
Signed-off-by: Chloé Vulquin <toast@bunkerlabs.net>
(cherry picked from commit 172c8add7d)
The spec reads:
> All paths set in these environment variables must be absolute. If an
> implementation encounters a relative path in any of these variables it should
> consider the path invalid and ignore it.
and
> If $XDG_DATA_HOME is either not set or empty, a default equal to
> $HOME/.local/share should be used.
Testing that the path is absolute also entails that is is non-empty.
The libXcursor fix for CVE-2013-2003 has never been imported into
wlroots, leaving it vulnerable to it.
Changing the argument type to an unsigned type is an effective merge of
Ilja Van Sprundel's commit in libXcursor.
Proof of Concept (compile with address sanitizer):
$ mkdir -p ~/.local/share/icons/poc/cursors
$ base64 -d <<< WGN1chAAAAAAAAAA/////w== > \
~/.local/share/icons/poc/cursors/poc
$ echo "seat seat0 xcursor_theme poc 10" > ~/poc-config
$ sway -c ~/poc-config
This reverts commit 7dffe9339b, which introduced
another linter error with -O3:
error: ‘strncat’ specified bound 7 equals source length [-Werror=stringop-overflow=]
This makes sense because strncat(dest, "cursors", strlen("cursors")) is moot
in security point of view.
The next commit will replace strncpy() with memcpy(), so let's restore the
original implementation.
Fix false positive stringop-truncation warning/error with GCC 10 on s390x by indicating GCC to explicitly ignore this case, as it is clearly a false positive (NUL is set in the following line).
This allow the compilation to succeed with -Werror on.
Fixes: https://github.com/swaywm/wlroots/issues/2018
Without the casts the bytes accesses get converted to int. but int is
not guaranteed to be 4 bytes large. Even when it is 4 bytes large
`bytes[3] << 24` does not fit because int is signed.
Nowadays ~/.icons is not used anymore as the preferred location for custom
user icon themes; XDG_DATA_HOME/icons (aka ~/.local/share/icons) is what
toolkits like GTK prefer. Prepend that location to the default xcursor path, so
that cursor themes installed there can be used by apps and toolkits that use
libXcursor.
Port of https://cgit.freedesktop.org/xorg/lib/libXcursor/commit/src?id=2263c196cb0dcb8547b378df7b35f83b8b99c01e
It is possible to trigger heap overflows due to an integer overflow
while parsing images.
The integer overflow occurs because the chosen limit 0x10000 for
dimensions is too large for 32 bit systems, because each pixel takes
4 bytes. Properly chosen values allow an overflow which in turn will
lead to less allocated memory than needed for subsequent reads.
See also:
https://cgit.freedesktop.org/xorg/lib/libXcursor/commit/?id=4794b5dd34688158fb51a2943032569d3780c4b85d201df72f
