Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754172AbaGDRZ0 (ORCPT ); Fri, 4 Jul 2014 13:25:26 -0400 Received: from mail-la0-f43.google.com ([209.85.215.43]:34388 "EHLO mail-la0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752832AbaGDRZY (ORCPT ); Fri, 4 Jul 2014 13:25:24 -0400 Date: Fri, 4 Jul 2014 19:24:57 +0200 From: Emil Goode To: Rickard Strandqvist Cc: Wolfram Sang , Grant Likely , Rob Herring , Jingoo Han , Leilei Shang , Peter Korsgaard , linux-i2c@vger.kernel.org, "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" Subject: Re: [PATCH v3] i2c: busses: i2c-pxa.c: Fix for possible null pointer dereferenc Message-ID: <20140704172457.GA3404@lianli> References: <1404418756-10550-1-git-send-email-rickard_strandqvist@spectrumdigital.se> <1404418756-10550-2-git-send-email-rickard_strandqvist@spectrumdigital.se> <20140704091000.GA4738@lianli> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Hello, I noticed one more thing. On Fri, Jul 04, 2014 at 07:07:48PM +0200, Rickard Strandqvist wrote: > 2014-07-04 11:10 GMT+02:00 Emil Goode : > > Hello Rickard, > > > > Since this is a probe function there is also no need to release the devm_* > > resources in the i2c_pxa_remove function, this leads to double free. > > > > Also I have a few nit-pick comments below. > > > > On Thu, Jul 03, 2014 at 10:19:16PM +0200, Rickard Strandqvist wrote: > >> Fix for possible null pointer dereferenc, and there is a risk for memory leak if something unexpected happens and the function returns. > >> It now use Managed Device Resource instead. > >> > >> Signed-off-by: Rickard Strandqvist > >> --- > >> drivers/i2c/busses/i2c-pxa.c | 37 ++++++++++++++++--------------------- > >> 1 file changed, 16 insertions(+), 21 deletions(-) > >> > >> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c > >> index be671f7..2edb633 100644 > >> --- a/drivers/i2c/busses/i2c-pxa.c > >> +++ b/drivers/i2c/busses/i2c-pxa.c > >> @@ -1141,10 +1141,10 @@ static int i2c_pxa_probe(struct platform_device *dev) > >> struct resource *res = NULL; > >> int ret, irq; > >> > >> - i2c = kzalloc(sizeof(struct pxa_i2c), GFP_KERNEL); > >> + i2c = devm_kzalloc(&dev->dev, sizeof(struct pxa_i2c), GFP_KERNEL); > >> if (!i2c) { > >> ret = -ENOMEM; > >> - goto emalloc; > >> + goto err_nothing_to_release; > > > > Perhaps its a good idea to return directly here, then the label > > err_nothing_to_release can be removed. > > > >> } > >> > >> /* Default adapter num to device id; i2c_pxa_probe_dt can override. */ > >> @@ -1154,18 +1154,19 @@ static int i2c_pxa_probe(struct platform_device *dev) > >> if (ret > 0) > >> ret = i2c_pxa_probe_pdata(dev, i2c, &i2c_type); > >> if (ret < 0) > >> - goto eclk; > >> + goto err_nothing_to_release; > > > > Same here. > > > >> > >> res = platform_get_resource(dev, IORESOURCE_MEM, 0); > >> irq = platform_get_irq(dev, 0); > >> if (res == NULL || irq < 0) { > >> ret = -ENODEV; > >> - goto eclk; > >> + goto err_nothing_to_release; > > > > Same here. > > > >> } > >> > >> - if (!request_mem_region(res->start, resource_size(res), res->name)) { > >> + if (!devm_request_mem_region(&dev->dev, res->start, > >> + resource_size(res), res->name)) { > >> ret = -ENOMEM; > >> - goto eclk; > >> + goto emalloc; > > > > We could also return directly here since the release_mem_region call should > > be removed, as mentioned in Jingoos reply. > > > >> } > >> > >> i2c->adap.owner = THIS_MODULE; > >> @@ -1176,16 +1177,16 @@ static int i2c_pxa_probe(struct platform_device *dev) > >> > >> strlcpy(i2c->adap.name, "pxa_i2c-i2c", sizeof(i2c->adap.name)); > >> > >> - i2c->clk = clk_get(&dev->dev, NULL); > >> + i2c->clk = devm_clk_get(&dev->dev, NULL); > >> if (IS_ERR(i2c->clk)) { > >> ret = PTR_ERR(i2c->clk); > >> - goto eclk; > >> + goto emalloc; > > > > Same here. > > > >> } > >> > >> - i2c->reg_base = ioremap(res->start, resource_size(res)); > >> - if (!i2c->reg_base) { > >> + i2c->reg_base = devm_ioremap_resource(&adev->dev, res)); > >> + if (IS_ERR(i2c->reg_base)) { > >> ret = -EIO; > >> - goto eremap; > >> + goto emalloc; > > > > Same here. > > > >> } > >> > >> i2c->reg_ibmr = i2c->reg_base + pxa_reg_layout[i2c_type].ibmr; > >> @@ -1227,10 +1228,10 @@ static int i2c_pxa_probe(struct platform_device *dev) > >> i2c->adap.algo = &i2c_pxa_pio_algorithm; > >> } else { > >> i2c->adap.algo = &i2c_pxa_algorithm; > >> - ret = request_irq(irq, i2c_pxa_handler, IRQF_SHARED, > >> - dev_name(&dev->dev), i2c); > >> + ret = devm_request_irq(&dev->dev, irq, i2c_pxa_handler, > >> + IRQF_SHARED, dev_name(&dev->dev), i2c); > >> if (ret) > >> - goto ereqirq; > >> + goto emalloc; > > > > Same here. > > > >> } > >> > >> i2c_pxa_reset(i2c); > >> @@ -1261,15 +1262,9 @@ static int i2c_pxa_probe(struct platform_device *dev) > >> eadapt: > >> if (!i2c->use_pio) > >> free_irq(irq, i2c); > > > > The free_irq() call should also be removed since devm_request_irq() was used. > > > >> -ereqirq: > >> - clk_disable_unprepare(i2c->clk); I think we should keep the clk_disable_unprepare() call. > >> - iounmap(i2c->reg_base); > >> -eremap: > >> - clk_put(i2c->clk); > >> -eclk: > >> - kfree(i2c); > >> emalloc: > >> release_mem_region(res->start, resource_size(res)); > >> +err_nothing_to_release: > >> return ret; > >> } > >> > > > > Best regards, > > > > Emil Goode > > Hi All! > > Ok, so there is literally nothing to do release anymore. > A good system Devres, I understand you want everyone to use it. > > I also think it is also better to return directly then. > But who decides, Wolfram? Yes, Wolfram is the maintainer. Personally I would do the devm_* convertion in a second patch. Best regards, Emil Goode -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/