Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755571AbbKYCUP (ORCPT ); Tue, 24 Nov 2015 21:20:15 -0500 Received: from eusmtp01.atmel.com ([212.144.249.242]:6566 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754922AbbKYCUM (ORCPT ); Tue, 24 Nov 2015 21:20:12 -0500 Subject: Re: [PATCH v2 2/2] mtd: nand: atmel_nand: fix a possible NULL dereference To: LABBE Corentin References: <1448005517-26004-1-git-send-email-clabbe.montjoie@gmail.com> <1448005517-26004-3-git-send-email-clabbe.montjoie@gmail.com> <564EDACA.30204@atmel.com> <20151124131218.GA7545@Red> CC: , , , From: Josh Wu Message-ID: <56551AD2.3010607@atmel.com> Date: Wed, 25 Nov 2015 10:20:02 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151124131218.GA7545@Red> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.168.5.13] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2212 Lines: 66 Hi, Corentin On 11/24/2015 9:12 PM, LABBE Corentin wrote: > On Fri, Nov 20, 2015 at 04:33:14PM +0800, Josh Wu wrote: >> Hi, Corentin >> >> Thanks for the patch. It looks fine to me, just one nitpick in below: >> >> On 11/20/2015 3:45 PM, LABBE Corentin wrote: >>> of_match_device could return NULL, and so cause a NULL pointer >>> dereference later. >>> >>> Signed-off-by: LABBE Corentin >>> --- >>> drivers/mtd/nand/atmel_nand.c | 5 +++-- >>> 1 file changed, 3 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c >>> index 475c938..7902967 100644 >>> --- a/drivers/mtd/nand/atmel_nand.c >>> +++ b/drivers/mtd/nand/atmel_nand.c >>> @@ -1496,8 +1496,9 @@ static int atmel_of_init_port(struct atmel_nand_host *host, >>> struct atmel_nand_data *board = &host->board; >>> enum of_gpio_flags flags = 0; >>> >>> - host->caps = (struct atmel_nand_caps *) >>> - of_match_device(atmel_nand_dt_ids, host->dev)->data; >>> + host->caps = of_device_get_match_data(host->dev); >>> + if (!host->caps) >>> + return 1; >> it's better to use -EINVAL here. >> > Hello > > I do that Uwe Kleine-K?nig said to me to do in others thread: > https://lkml.org/lkml/2015/11/12/70 and https://lkml.org/lkml/2015/11/16/211 Thank you for the information. I checked the imx serial driver(drivers/tty/serial/imx.c) in serial_imx_probe(): ... ret = serial_imx_probe_dt(sport, pdev); if (ret > 0) ---> So here is why you need to return 1 in serial_imx_probe_dt(). serial_imx_probe_pdata(sport, pdev); else if (ret < 0) return ret; There has a branch to check whether ret is > 0 or < 0. So that's why you need to return 1 in imx serial driver. But in atmel_nand driver, we don't have such code for that. The atmel_of_init_port() is only used for dt probe. So if dt is not matched, just return an error. > > Regards > Best Regards, Josh Wu -- 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/