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Miller" , Eric Dumazet , Paolo Abeni , Russell King , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Bobby Eshleman Subject: Re: [PATCH net] eth: fbnic: fix double-free of PCS on phylink creation failure Message-ID: References: <20260416-fbnic-pcs-fix-v1-1-ac4b6badeac0@meta.com> <1873b5ba-419f-4247-ab92-1b5e899458e8@lunn.ch> <49138791-0726-4065-a772-56fea43070b7@lunn.ch> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49138791-0726-4065-a772-56fea43070b7@lunn.ch> On Fri, Apr 17, 2026 at 01:48:38AM +0200, Andrew Lunn wrote: > > diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c > > index e3ca5fcfabef..2a6a73393732 100644 > > --- a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c > > +++ b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c > > @@ -818,7 +818,8 @@ struct net_device *fbnic_netdev_alloc(struct fbnic_dev *fbd) > > netif_tx_stop_all_queues(netdev); > > > > if (fbnic_phylink_create(netdev)) { > > - fbnic_netdev_free(fbd); > > + free_netdev(netdev); > > + fbd->netdev = NULL; > > Why set it to NULL? Setting pointers to NULL like this often suggests > you are not confident the code is correct and you are being > defensive. It is better to review the code and be sure it does the > correct thing. > > > return NULL; > > } > > > > diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_phylink.c b/drivers/net/ethernet/meta/fbnic/fbnic_phylink.c > > index 09c5225111be..50240e6c2ee9 100644 > > --- a/drivers/net/ethernet/meta/fbnic/fbnic_phylink.c > > +++ b/drivers/net/ethernet/meta/fbnic/fbnic_phylink.c > > @@ -237,6 +237,7 @@ int fbnic_phylink_create(struct net_device *netdev) > > dev_err(netdev->dev.parent, > > "Failed to create Phylink interface, err: %d\n", err); > > xpcs_destroy_pcs(pcs); > > + fbn->pcs = NULL; > > Why set it to NULL? If it failed, you are unwinding and about to fail > the probe. Nothing should be using it. > > I would also say fbnic_phylink_destroy() is wrong or at least whoever > wrote it is not confident in there own code. It should only be called > if fbnic_phylink_create() was successful, so you know fbn->pcs is > valid, so there is no need to test it. The same for fbn->phylink. > > Andrew Fair points. I think it looks sound without resetting to NULL, but I'll double check and remove if confident. I'll look at the checks in _destroy() too. Thanks, Bobby