SIGSEGV when activating on empty desktop

[arkq]

When activating skippy on an empty desktop with no faked root window (e.g. fluxbox), uninitialized pointer is freed.

It is caused by the fact that XGetInputFocus returns PointerRoot in this case, which is not checked. Passing this value as a window ID causes X* functions to fail. In the final results uninitialized pointer is freed (wm.c function wm_get_focused line XFree(children)).

Proposed patch:

Bug fix: Proper handling of the PointerRoot focus

Fix a SIGSEGV issue when input focus is on the X root window. In that case,
XGetInputFocus returns PointerRoot, which can not be passed as a valid
window ID.

Signed-off-by: Arkadiusz Bokowy <arkadiusz.bokowy@gmail.com>

---
 src/wm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/wm.c b/src/wm.c
index bebf44c..91b7c06 100644
--- a/src/wm.c
+++ b/src/wm.c
@@ -626,8 +626,8 @@ wm_get_focused(Display *dpy)
    unsigned char *data;

    XGetInputFocus(dpy, &focused, &revert_to);
-   
-   while(focused != None && focused != root)
+
+   while(focused != None && focused != PointerRoot && focused != root)
    {
        status = XGetWindowProperty(dpy, focused, XA_WM_STATE,
                                    0L, 1L, False, XA_WM_STATE, &real_type, &real_format,
--
1.8.3.2

[richardgv]

Thanks for the report and the patch, Arkq! Although I'm not able to let XGetInputFocus() return PointerRoot under Flubox somehow, I rewrote wm_get_focused() to fix all the little issues inside. (58b752f) Does it work for you right now?

[arkq]

Yes, right now everything works just fine. Thanks.