Received-SPF: pass (google.com: domain of linux-kernel+bounces-108545-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Wed, 20 Mar 2024 08:32:17 +0100 (CET)
From: Julia Lawall <julia.lawall@inria.fr>
To: Dan Carpenter <dan.carpenter@linaro.org>
cc: Jakub Kicinski <kuba@kernel.org>, 
    Maciej Fijalkowski <maciej.fijalkowski@intel.com>, 
    Jesse Brandeburg <jesse.brandeburg@intel.com>, 
    Tony Nguyen <anthony.l.nguyen@intel.com>, 
    "David S. Miller" <davem@davemloft.net>, 
    Eric Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, 
    Przemek Kitszel <przemyslaw.kitszel@intel.com>, 
    intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, 
    linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, 
    Jonathan Cameron <jic23@kernel.org>
Subject: Re: [PATCH net] ice: Fix freeing uninitialized pointers
In-Reply-To: <facf5615-d7ac-4167-b23c-6bab7c123138@moroto.mountain>
Message-ID: <f1bdbed9-8549-3787-bd17-ecd62851e8a@inria.fr>
References: <77145930-e3df-4e77-a22d-04851cf3a426@moroto.mountain> <20240319124317.3c3f16cd@kernel.org> <facf5615-d7ac-4167-b23c-6bab7c123138@moroto.mountain>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII


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