From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752014AbdAaSWq (ORCPT ); Tue, 31 Jan 2017 13:22:46 -0500 Received: from mail.kernel.org ([198.145.29.136]:54084 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751417AbdAaSWg (ORCPT ); Tue, 31 Jan 2017 13:22:36 -0500 Date: Tue, 31 Jan 2017 12:22:32 -0600 From: Bjorn Helgaas To: Shailendra Verma Cc: Zhou Wang , Gabriele Paoloni , Bjorn Helgaas , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, p.shailesh@samsung.com, ashish.kalra@samsung.com, Shailendra Verma Subject: Re: [PATCH] Pci: host - Fix possible NULL derefrence. Message-ID: <20170131182232.GA18672@bhelgaas-glaptop.roam.corp.google.com> References: <1485751775-29126-1-git-send-email-shailendra.v@samsung.com> <20170131150900.GB9942@bhelgaas-glaptop.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170131150900.GB9942@bhelgaas-glaptop.roam.corp.google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 31, 2017 at 09:09:00AM -0600, Bjorn Helgaas wrote: > Hi Shailendra, > > On Mon, Jan 30, 2017 at 10:19:35AM +0530, Shailendra Verma wrote: > > of_match_device could return NULL, and so can cause a NULL > > pointer dereference later. > > > > Signed-off-by: Shailendra Verma > > --- > > drivers/pci/host/pcie-hisi.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/drivers/pci/host/pcie-hisi.c b/drivers/pci/host/pcie-hisi.c > > index 56154c2..3256f8f 100644 > > --- a/drivers/pci/host/pcie-hisi.c > > +++ b/drivers/pci/host/pcie-hisi.c > > @@ -174,6 +174,10 @@ static int hisi_pcie_probe(struct platform_device *pdev) > > driver = dev->driver; > > > > match = of_match_device(driver->of_match_table, dev); > > + if (!match) { > > + dev_err(dev, "Error: No device match found\n"); > > + return -ENODEV; > > + } > > hisi_pcie->soc_ops = (struct pcie_soc_ops *) match->data; > > > > hisi_pcie->subctrl = > > I like this patch and I think it's correct. I'd like an ack from Zhou > and/or Gabriele, and I'd propose the following tweak, which just moves the > check earlier, before we start allocating this: Geert pointed out in a similar case that it's actually impossible for match to be NULL here because the only way to call hisi_pcie_probe() is to match an entry in hisi_pcie_of_match[]. So I think the following patch is even better because it removes a mention of driver->of_match_table. I can't easily build test to be sure, but I think the cast is also unnecessary. commit 806d19760e48166505818d4efafbdfbad5810989 Author: Shailendra Verma Date: Mon Jan 30 10:19:35 2017 +0530 PCI: hisi: Use of_device_get_match_data() to simplify probe The only way to call hisi_pcie_probe() is to match an entry in hisi_pcie_of_match[], so match cannot be NULL. Use of_device_get_match_data() to retrieve the soc_ops pointer. No functional change intended. [bhelgaas: use of_device_get_match_data(), changelog] Based-on-suggestion-from: Geert Uytterhoeven Signed-off-by: Shailendra Verma Signed-off-by: Bjorn Helgaas diff --git a/drivers/pci/host/pcie-hisi.c b/drivers/pci/host/pcie-hisi.c index a301a7187b30..34d10d242225 100644 --- a/drivers/pci/host/pcie-hisi.c +++ b/drivers/pci/host/pcie-hisi.c @@ -259,7 +259,6 @@ static int hisi_pcie_probe(struct platform_device *pdev) struct device *dev = &pdev->dev; struct hisi_pcie *hisi_pcie; struct pcie_port *pp; - const struct of_device_id *match; struct resource *reg; struct device_driver *driver; int ret; @@ -272,11 +271,10 @@ static int hisi_pcie_probe(struct platform_device *pdev) pp->dev = dev; driver = dev->driver; - match = of_match_device(driver->of_match_table, dev); - hisi_pcie->soc_ops = (struct pcie_soc_ops *) match->data; + hisi_pcie->soc_ops = of_device_get_match_data(dev); hisi_pcie->subctrl = - syscon_regmap_lookup_by_compatible("hisilicon,pcie-sas-subctrl"); + syscon_regmap_lookup_by_compatible("hisilicon,pcie-sas-subctrl"); if (IS_ERR(hisi_pcie->subctrl)) { dev_err(dev, "cannot get subctrl base\n"); return PTR_ERR(hisi_pcie->subctrl);