isa/gnome-shell
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

st: Avoid integer overflow on unpremultiply

Browse Source 
When computing the effective border color, we operate on colors with
premultiplied alpha to simplify the calculations, then unpremultiply
the result. However we miss a bounds check in the last check, so any
color component can overflow the allowed maximum of 0xff and shift the
result in unexpected ways.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/305
This commit is contained in:
Florian Müllner 2018-11-22 20:41:44 +01:00 committed by Florian Müllner
parent 6743c18fdf
commit 925a25da17
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/st/st-theme-node-drawing.c
View File

@ -229,9 +229,9 @@ unpremultiply (ClutterColor *color)
{
if (color->alpha != 0)
{
color->red = (color->red * 255 + 127) / color->alpha;
color->green = (color->green * 255 + 127) / color->alpha;
color->blue = (color->blue * 255 + 127) / color->alpha;
color->red = MIN((color->red * 255 + 127) / color->alpha, 255);
color->green = MIN((color->green * 255 + 127) / color->alpha, 255);
color->blue = MIN((color->blue * 255 + 127) / color->alpha, 255);
}
}