Comment 28 for bug 1751252

Getting closer. It's this failing in the Xorg process:

        /* The attach was performed with root privs. We must
         * do manual checking of access rights for the credentials
         * of the client */

        if (shm_access(client, &(SHM_PERM(buf)), stuff->readOnly) == -1) {
            shmdt(shmdesc->addr);
            free(shmdesc);
            return BadAccess;
        }