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

[Dan Carpenter]

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.

regards,
dan carpenter