Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752010Ab1EIPGZ (ORCPT ); Mon, 9 May 2011 11:06:25 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:56602 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750879Ab1EIPGX (ORCPT ); Mon, 9 May 2011 11:06:23 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=RpIDVfUgmDjzJFETzB3rxaUZnFz7LIK9Lj2ZmTSjul94OFN8hMONfaXjxByvc4W0/n 71zhXXjygyRLW4toMbnWllHLc6DKggCYNdnsxD+b1fdsIcPBpUfFDogWgBFM21HTeQCd Zg8IiuT7qtHl3ux1YZrQo5plzhoAPNTt7V4HU= Message-ID: <4DC802C0.9040302@gmail.com> Date: Mon, 09 May 2011 17:05:36 +0200 From: Vladimir Motyka User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.17) Gecko/20110414 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: Julia Lawall CC: cjb@laptop.org, kernel-janitors@vger.kernel.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drivers/mmc/card/block.c: fix potential null dereference 'idata' References: <4DC7F4AB.90607@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2209 Lines: 79 On 05/09/2011 04:32 PM, Julia Lawall wrote: > On Mon, 9 May 2011, Vladimir Motyka wrote: > >> When allocation of idata fails there was a null dereferece. > > Why not have a different label for the two cases? That would make the > code easier to statically analyze, and perhaps be more understandable as > well. > > julia > I think You are right. So it could be better like this? diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index 3dec493..a03cdc6 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -237,7 +237,7 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user( idata = kzalloc(sizeof(*idata), GFP_KERNEL); if (!idata) { err = -ENOMEM; - goto copy_err; + goto alloc_err; } if (copy_from_user(&idata->ic, user, sizeof(idata->ic))) { @@ -266,9 +266,9 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user( return idata; copy_err: - if(idata) - kfree(idata->buf); + kfree(idata->buf); kfree(idata); +alloc_err: return ERR_PTR(err); } Or it could return right after allocation fails so there needn't be goto. It is simplier, but maybe worse looking and to read. What is your opinion? Vladimir Motyka > >> Signed-off-by: Vladimir Motyka >> >> --- >> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c >> index 407836d..3dec493 100644 >> --- a/drivers/mmc/card/block.c >> +++ b/drivers/mmc/card/block.c >> @@ -266,10 +266,10 @@ static struct mmc_blk_ioc_data >> *mmc_blk_ioctl_copy_from_user( >> return idata; >> >> copy_err: >> - kfree(idata->buf); >> + if(idata) >> + kfree(idata->buf); >> kfree(idata); >> return ERR_PTR(err); >> - >> } >> >> static int mmc_blk_ioctl_cmd(struct block_device *bdev, >> -- >> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> -- 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/