From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89FB4C10F27 for ; Mon, 9 Mar 2020 18:30:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 688FC205F4 for ; Mon, 9 Mar 2020 18:30:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727421AbgCISaE (ORCPT ); Mon, 9 Mar 2020 14:30:04 -0400 Received: from foss.arm.com ([217.140.110.172]:56132 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727334AbgCISaE (ORCPT ); Mon, 9 Mar 2020 14:30:04 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8606C1FB; Mon, 9 Mar 2020 11:30:03 -0700 (PDT) Received: from donnerap.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 42EEA3F67D; Mon, 9 Mar 2020 11:30:02 -0700 (PDT) Date: Mon, 9 Mar 2020 18:29:59 +0000 From: Andre Przywara To: "David S . Miller" , Radhey Shyam Pandey Cc: Michal Simek , Robert Hancock , netdev@vger.kernel.org, rmk+kernel@arm.linux.org.uk, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Andrew Lunn Subject: Re: [PATCH v2 04/14] net: axienet: Fix DMA descriptor cleanup path Message-ID: <20200309182959.080fa773@donnerap.cambridge.arm.com> In-Reply-To: <20200309181851.190164-5-andre.przywara@arm.com> References: <20200309181851.190164-1-andre.przywara@arm.com> <20200309181851.190164-5-andre.przywara@arm.com> Organization: ARM X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; aarch64-unknown-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 9 Mar 2020 18:18:41 +0000 Andre Przywara wrote: Hi Radhey, you looked at this patch before, it was [PATCH 03/14] back then. You ended up saying "Looks fine then.", but I didn't dare to convert this into a "Reviewed-by:" tag. Just a hint that I didn't change anything, that might simplify the review. Cheers, Andre > When axienet_dma_bd_init() bails out during the initialisation process, > it might do so with parts of the structure already allocated and > initialised, while other parts have not been touched yet. Before > returning in this case, we call axienet_dma_bd_release(), which does not > take care of this corner case. > This is most obvious by the first loop happily dereferencing > lp->rx_bd_v, which we actually check to be non NULL *afterwards*. > > Make sure we only unmap or free already allocated structures, by: > - directly returning with -ENOMEM if nothing has been allocated at all > - checking for lp->rx_bd_v to be non-NULL *before* using it > - only unmapping allocated DMA RX regions > > This avoids NULL pointer dereferences when initialisation fails. > > Signed-off-by: Andre Przywara > --- > .../net/ethernet/xilinx/xilinx_axienet_main.c | 43 ++++++++++++------- > 1 file changed, 28 insertions(+), 15 deletions(-) > > diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > index 64f73533cabe..9903205d57ec 100644 > --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > @@ -160,24 +160,37 @@ static void axienet_dma_bd_release(struct net_device *ndev) > int i; > struct axienet_local *lp = netdev_priv(ndev); > > + /* If we end up here, tx_bd_v must have been DMA allocated. */ > + dma_free_coherent(ndev->dev.parent, > + sizeof(*lp->tx_bd_v) * lp->tx_bd_num, > + lp->tx_bd_v, > + lp->tx_bd_p); > + > + if (!lp->rx_bd_v) > + return; > + > for (i = 0; i < lp->rx_bd_num; i++) { > - dma_unmap_single(ndev->dev.parent, lp->rx_bd_v[i].phys, > - lp->max_frm_size, DMA_FROM_DEVICE); > + /* A NULL skb means this descriptor has not been initialised > + * at all. > + */ > + if (!lp->rx_bd_v[i].skb) > + break; > + > dev_kfree_skb(lp->rx_bd_v[i].skb); > - } > > - if (lp->rx_bd_v) { > - dma_free_coherent(ndev->dev.parent, > - sizeof(*lp->rx_bd_v) * lp->rx_bd_num, > - lp->rx_bd_v, > - lp->rx_bd_p); > - } > - if (lp->tx_bd_v) { > - dma_free_coherent(ndev->dev.parent, > - sizeof(*lp->tx_bd_v) * lp->tx_bd_num, > - lp->tx_bd_v, > - lp->tx_bd_p); > + /* For each descriptor, we programmed cntrl with the (non-zero) > + * descriptor size, after it had been successfully allocated. > + * So a non-zero value in there means we need to unmap it. > + */ > + if (lp->rx_bd_v[i].cntrl) > + dma_unmap_single(ndev->dev.parent, lp->rx_bd_v[i].phys, > + lp->max_frm_size, DMA_FROM_DEVICE); > } > + > + dma_free_coherent(ndev->dev.parent, > + sizeof(*lp->rx_bd_v) * lp->rx_bd_num, > + lp->rx_bd_v, > + lp->rx_bd_p); > } > > /** > @@ -207,7 +220,7 @@ static int axienet_dma_bd_init(struct net_device *ndev) > sizeof(*lp->tx_bd_v) * lp->tx_bd_num, > &lp->tx_bd_p, GFP_KERNEL); > if (!lp->tx_bd_v) > - goto out; > + return -ENOMEM; > > lp->rx_bd_v = dma_alloc_coherent(ndev->dev.parent, > sizeof(*lp->rx_bd_v) * lp->rx_bd_num,