On Wed, 29 Jan 2014 20:39:41 -0500 Michael Blumenkrantz
<michael.blumenkra...@gmail.com> said:

> On Thu, 30 Jan 2014 10:32:26 +0900
> Carsten Haitzler (The Rasterman) <ras...@rasterman.com> wrote:
> 
> > On Wed, 29 Jan 2014 20:23:46 -0500 Michael Blumenkrantz
> > <michael.blumenkra...@gmail.com> said:
> > 
> > > On Wed, 29 Jan 2014 16:01:10 -0800
> > > Carsten Haitzler <ras...@rasterman.com> wrote:
> > > 
> > > > raster pushed a commit to branch master.
> > > > 
> > > > http://git.enlightenment.org/core/enlightenment.git/commit/?id=83397e1bde51830016e9a0f8e6482fc91bb4c50c
> > > > 
> > > > commit 83397e1bde51830016e9a0f8e6482fc91bb4c50c
> > > > Author: Carsten Haitzler (Rasterman) <ras...@rasterman.com>
> > > > Date:   Thu Jan 30 08:55:28 2014 +0900
> > > > 
> > > >     fix segv where comp_data is null but still accessed
> > > >     
> > > >     it seems i have an override-redirect window just off the
> > > > bottom-right of my screen - i think its the scim input panel status.
> > > > what happens is it is "managed" by comp but then deleted
> > > > (_e_comp_x_hook_client_del called), BUT _e_comp_x_object_add is called
> > > > with a deferred event for that client to add it again (likely this is a
> > > > race) which finds he client in a state of not having comp_data as the
> > > > E_FREE in _e_comp_x_hook_client_del() frees it and sets it to NULL.
> > > > move the comp_data free to the actual client free (which is the last
> > > > time a client is valid at all) solves this.
> > > > ---
> > > >  src/bin/e_client.c | 1 +
> > > >  src/bin/e_comp_x.c | 1 -
> > > >  2 files changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > 
> > > I guess I'll have to take a look at this. Freeing comp_data in
> > > _e_client_free () is wrong in all cases since it's compositor-specific
> > > and guarantees that data will leak.
> > 
> > eh? how does it guarantee it will leak? a client free frees the comp_data -
> > you'd otherwise have to never free a client to never free the comp data set
> > ON the client itself. so yes - it's a leak if clients are never freed...
> > whic is a leak in and of itself.
> > 
> > simply - it's not a leak now. sure - it's not freed int he same domain where
> > it's allocated - that is true, but the problem is that if that is left
> > there it is ACCESSED in the same domain after being freed - the client is
> > still attached to an object, but the comp data has been freed for the
> > client. so the logical options are to enusre the objects are deleted at the
> > point the comp data is freed OR defer the comp data free until the client
> > is actually freed/cleaned up. i chose option 2 since it had no leaks and
> > was the least amount of changes.
> > 
> 
> I think you are misunderstanding what I'm saying. The comp_data struct itself
> won't leak, but everything in it will leak since this is opaque. Freeing it
> there is a poor workaround to fixing the underlying bug.

look at the patch... everything inside of it is free/deleted in the same spot.
just the struct ITSELF it deferred to be freed later. so we keep an empty
"comp_data" struct. yeah - i should have nul/0'd out comp_data->damage as that
is freed but still left as a valid resource ref. all of the rest of the
deletion still happens in _e_comp_x_hook_client_del() EXCEPT the free of the
comp_data struct itself. THAT is the only thing not freed there - and JUST that
is deferred until client free so the comp_data ptr stays valid for as long as it
is assumed to exist/be valid (i read all the code accessing it - all the code
ASSUMES that if you have a client struct, comp_data is non-null and valid at
all times).

> I just hit this crash myself, and I'm testing a fix for it currently. So far
> it seems to be functioning well, so I'll likely have it up soon.


-- 
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    ras...@rasterman.com


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