dix: Allow zero-height PutImage requests

The length checking code validates PutImage height and byte width by
making sure that byte-width >= INT32_MAX / height. If height is zero,
this generates a divide by zero exception. Allow zero height requests
explicitly, bypassing the INT32_MAX check.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>

dix/dispatch.c

@@ -2000,7 +2000,7 @@ ProcPutImage(ClientPtr client)
     tmpImage = (char *) &stuff[1];
     lengthProto = length;
 
-    if (lengthProto >= (INT32_MAX / stuff->height))
+    if (stuff->height != 0 && lengthProto >= (INT32_MAX / stuff->height))
         return BadLength;
 
     if ((bytes_to_int32(lengthProto * stuff->height) +