From ce02d030202249b6df7ccca83aed5371deef4958 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Sat, 18 Apr 2026 07:35:15 +1000
Subject: [PATCH] xkb: Fix off-by-one in color index validation in
 _CheckSetGeom()

The bounds checks for baseColorNdx and labelColorNdx in _CheckSetGeom()
use '>' instead of '>=' when comparing against req->nColors. Since
nColors is a count and valid indices are 0 to nColors-1, an index equal
to nColors is one past the end of the array.

Assisted-by: Claude:claude-claude-opus-4-6
(cherry picked from commit 6b6e8020b902e48e3330f9a54cd439a51988bc50)

Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2225>
---
 xkb/xkb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xkb/xkb.c b/xkb/xkb.c
index f875a70c7..107284cff 100644
--- a/xkb/xkb.c
+++ b/xkb/xkb.c
@@ -5626,12 +5626,12 @@ _CheckSetGeom(XkbGeometryPtr geom, xkbSetGeometryReq * req, ClientPtr client)
         client->errorValue = _XkbErrCode3(0x01, 2, req->nColors);
         return BadValue;
     }
-    if (req->baseColorNdx > req->nColors) {
+    if (req->baseColorNdx >= req->nColors) {
         client->errorValue =
             _XkbErrCode3(0x03, req->nColors, req->baseColorNdx);
         return BadMatch;
     }
-    if (req->labelColorNdx > req->nColors) {
+    if (req->labelColorNdx >= req->nColors) {
         client->errorValue =
             _XkbErrCode3(0x03, req->nColors, req->labelColorNdx);
         return BadMatch;