Import Debian changes 2:1.20.4-1+deb10u3

Xi/chgfctl.c

@@ -464,8 +464,11 @@ ProcXChangeFeedbackControl(ClientPtr client)
         break;
     case StringFeedbackClass:
     {
-        xStringFeedbackCtl *f = ((xStringFeedbackCtl *) &stuff[1]);
+        xStringFeedbackCtl *f;
 
+        REQUEST_AT_LEAST_EXTRA_SIZE(xChangeFeedbackControlReq,
+                                    sizeof(xStringFeedbackCtl));
+        f = ((xStringFeedbackCtl *) &stuff[1]);
         if (client->swapped) {
             if (len < bytes_to_int32(sizeof(xStringFeedbackCtl)))
                 return BadLength;

debian/changelog

+xorg-server (2:1.20.4-1+deb10u3) buster-security; urgency=high
+
+  * Fix XChangeFeedbackControl() request underflow (CVE-2021-3472)
+
+ -- Julien Cristau <jcristau@debian.org>  Mon, 19 Apr 2021 11:34:38 +0200
+
 xorg-server (2:1.20.4-1+deb10u2) buster-security; urgency=medium
 
   * CVE-2020-14360 CVE-2020-25712