Re: [PATCH net] ice: Fix freeing uninitialized pointers

[Julia Lawall <julia.lawall@inria.fr>]

On Wed, 20 Mar 2024, Dan Carpenter wrote:

> On Tue, Mar 19, 2024 at 12:43:17PM -0700, Jakub Kicinski wrote:
> > On Sat, 16 Mar 2024 12:44:40 +0300 Dan Carpenter wrote:
> > > -	struct ice_aqc_get_phy_caps_data *pcaps __free(kfree);
> > > -	void *mac_buf __free(kfree);
> > > +	struct ice_aqc_get_phy_caps_data *pcaps __free(kfree) = NULL;
> > > +	void *mac_buf __free(kfree) = NULL;
> >
> > This is just trading one kind of bug for another, and the __free()
> > magic is at a cost of readability.
> >
> > I think we should ban the use of __free() in all of networking,
> > until / unless it cleanly handles the NULL init case.
>
> Free handles the NULL init case, it doesn't handle the uninitialized
> case.  I had previously argued that checkpatch should complain about
> every __free() pointer if the declaration doesn't have an assignment.
>
> The = NULL assignment is unnecessary if the pointer is assigned to
> something else before the first return, so this might cause "unused
> assignment" warnings?  I don't know if there are any tools which
> complain about that in that situation.  I think probably we should just
> make that an exception and do the checkpatch thing because it's such a
> simple rule to implement.

My understanding from Jonathan Cameron was that Linus wants a NULL always,
unless there is an initialization with the declaration.

julia