Am Dienstag, den 01.11.2011, 07:04 +0100 schrieb Milan Crha:
> On Mon, 2011-10-31 at 21:22 +0100, Thomas Mittelstaedt wrote:
> > Just had a segfault in gal_a11y_e_cell_popup_new. Turned out that
> > the cast
> > popupcell= E_CELL_POPUP (cell_view->ecell);
> >
> > would turn up a broken pointer, crashing afterward.
>
> Hi,
> it depends on the brokenness kind, if either the cell_view is already
> freed, or the cell_view->ecell is pointing to already freed memory. In
> both cases you are trying to access maybe-overwritten memory and read
> from it, which can do pretty much anything.
>
> > I inserted the following on my side:
> >
> > ECellPopup *popupcell = NULL;
> > ECellView* child_view = NULL;
> >
> > if (E_IS_CELL_POPUP(cell_view->ecell)) {
> > popupcell = E_CELL_POPUP(cell_view->ecell);
> > }
>
> That it didn't crash for you is probably just a coincidence, that the
> memory (allocated on GSlice) wasn't overwritten yet. You can check with
> valgrind, using command like this:
> $ G_SLICE=always-malloc valgrind --num-callers=50 evolution &>log.txt
>
> I suppose yours "Just had a segfault" also means that you do not face it
> every day, it just happened today, thus you do not have a reproducer for
> this?
You are right. I just had another crash with the above code changes. gdb
told me that
popupcell->popup_cell_view->cell_view.ecell was a broken pointer and
popupcell->popup_cell_view->cell_view.e_table_model was 0. So, I
inserted another "sanity check". Let's see if it crashes again.
--
thomas
Insert check to prevent crash
From: Thomas Mittelstaedt <tmsta...@t-mittelstaedt.de>
---
a11y/e-table/gal-a11y-e-cell-popup.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/a11y/e-table/gal-a11y-e-cell-popup.c
b/a11y/e-table/gal-a11y-e-cell-popup.c
index 141ce17..b5583fa 100644
--- a/a11y/e-table/gal-a11y-e-cell-popup.c
+++ b/a11y/e-table/gal-a11y-e-cell-popup.c
@@ -89,14 +89,19 @@ gal_a11y_e_cell_popup_new (ETableItem *item,
{
AtkObject *a11y;
GalA11yECell *cell;
- ECellPopup *popupcell;
+ ECellPopup *popupcell = NULL;
ECellView* child_view = NULL;
- popupcell= E_CELL_POPUP(cell_view->ecell);
+ if (E_IS_CELL_POPUP(cell_view->ecell)) {
+ popupcell = E_CELL_POPUP(cell_view->ecell);
+ }
+
+ if (popupcell && popupcell->popup_cell_view &&
+ popupcell->popup_cell_view->cell_view.e_table_model) {
- if (popupcell && popupcell->popup_cell_view)
child_view = popupcell->popup_cell_view->child_view;
-
+ }
+
if (child_view && child_view->ecell) {
a11y = gal_a11y_e_cell_registry_get_object (NULL,
item,
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