From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Gortmaker Subject: Re: [PATCH][net-next] gianfar: Fix alloc_skb_resources on -ENOMEM cleanup path Date: Thu, 8 Nov 2012 09:21:03 -0500 Message-ID: <509BBFCF.20109@windriver.com> References: <1352382008-7039-1-git-send-email-claudiu.manoil@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , "David S. Miller" To: Claudiu Manoil Return-path: Received: from mail.windriver.com ([147.11.1.11]:59632 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755976Ab2KHOVK (ORCPT ); Thu, 8 Nov 2012 09:21:10 -0500 In-Reply-To: <1352382008-7039-1-git-send-email-claudiu.manoil@freescale.com> Sender: netdev-owner@vger.kernel.org List-ID: On 12-11-08 08:40 AM, Claudiu Manoil wrote: > Should gfar_init_bds() return with -ENOMEM inside gfar_alloc_skb_resources(), > free_skb_resources() will be called twice in a row on the "cleanup" path, > leading to duplicate kfree() calls for rx_|tx_queue->rx_|tx_skbuff resulting > in segmentation fault. > This patch prevents the segmentation fault to happen in the future > (rx_|tx_sbkbuff set to NULL), and corrects the error path handling > for gfar_init_bds(). Since gfar_init_bds is more like a slave routine to gfar_alloc_skb_resources, I think the dup free_skb_resources should remain in the parent, and be removed from gfar_init_bds. Otherwise the gfar_alloc_skb_resources will appear confusing -- one will think it it allocates some resources, hits a failure and then returns without bothering to do any cleanup of the parts it did manage to allocate. (Then gfar_restore will have to call the free itself _if_ gfar_init_bds fails too.) Paul. -- > > Cc: Paul Gortmaker > Cc: "David S. Miller" > > Signed-off-by: Claudiu Manoil > --- > drivers/net/ethernet/freescale/gianfar.c | 8 ++++++-- > 1 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c > index 1d03dcd..c5c82ad 100644 > --- a/drivers/net/ethernet/freescale/gianfar.c > +++ b/drivers/net/ethernet/freescale/gianfar.c > @@ -311,7 +311,7 @@ static int gfar_alloc_skb_resources(struct net_device *ndev) > } > > if (gfar_init_bds(ndev)) > - goto cleanup; > + return -ENOMEM; > > return 0; > > @@ -1356,7 +1356,9 @@ static int gfar_restore(struct device *dev) > if (!netif_running(ndev)) > return 0; > > - gfar_init_bds(ndev); > + if (gfar_init_bds(ndev)) > + return -ENOMEM; > + > init_registers(ndev); > gfar_set_mac_address(ndev); > gfar_init_mac(ndev); > @@ -1709,6 +1711,7 @@ static void free_skb_tx_queue(struct gfar_priv_tx_q *tx_queue) > tx_queue->tx_skbuff[i] = NULL; > } > kfree(tx_queue->tx_skbuff); > + tx_queue->tx_skbuff = NULL; > } > > static void free_skb_rx_queue(struct gfar_priv_rx_q *rx_queue) > @@ -1732,6 +1735,7 @@ static void free_skb_rx_queue(struct gfar_priv_rx_q *rx_queue) > rxbdp++; > } > kfree(rx_queue->rx_skbuff); > + rx_queue->rx_skbuff = NULL; > } > > /* If there are any tx skbs or rx skbs still around, free them. >