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
