<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - user_elect_display() overwrites DISPLAY with TTY session when switching VT away from a graphical session" href="https://bugs.freedesktop.org/show_bug.cgi?id=90769#c1">Comment # 1</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - user_elect_display() overwrites DISPLAY with TTY session when switching VT away from a graphical session" href="https://bugs.freedesktop.org/show_bug.cgi?id=90769">bug 90769</a> from <a class="email" href="mailto:bugzilla@tecnocode.co.uk" title="Philip Withnall <bugzilla@tecnocode.co.uk>"> Philip Withnall</a> <pre>Created <a href="attachment.cgi?id=116145" name="attach_116145" title="logind: Fix user_elect_display() to be more stable">attachment 116145</a> <a href="attachment.cgi?id=116145&action=edit" title="logind: Fix user_elect_display() to be more stable">[details]</a> <a href='page.cgi?id=splinter.html&bug=90769&attachment=116145'>[review]</a> logind: Fix user_elect_display() to be more stable The previous implementation of user_elect_display() could easily end up overwriting the user’s valid graphical session with a new TTY session. For example, consider the situation where there is one session: c1, type = SESSION_X11, !stopping, class = SESSION_USER it is initially elected as the user’s display (i.e. u->display = c1). If another session is started, on a different VT, the sessions_by_user list becomes: c1, type = SESSION_X11, !stopping, class = SESSION_USER c2, type = SESSION_TTY, !stopping, class = SESSION_USER In the previous code, graphical = c1 and text = c2, as expected. However, neither graphical nor text fulfil the conditions for setting u->display = graphical (because neither is better than u->display), so the code falls through to check the text variable. The conditions for this match, as u->display->type != SESSION_TTY (it’s actually SESSION_X11). Hence u->display is set to c2, which is incorrect, because session c1 is still valid. Refactor user_elect_display() to use a more explicit filter and pre-order comparison over the sessions. This can be demonstrated to be stable and only ever ‘upgrade’ the session to a more graphical one.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>