From patchwork Mon May 9 15:05:36 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Motyka X-Patchwork-Id: 769562 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter2.kernel.org (8.14.4/8.14.3) with ESMTP id p49F6cM7004783 for ; Mon, 9 May 2011 15:06:38 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751758Ab1EIPGY (ORCPT ); Mon, 9 May 2011 11:06:24 -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 Received: by bwz15 with SMTP id 15so4050121bwz.19 for ; Mon, 09 May 2011 08:06:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=ioBgRSOYypZEZBDuV9xUKkkPX2sFFpEgVLSS4hq25u8=; b=Q0C/s4twtupKv67ezWzlBEEnNxco9AqQ90uSNUkE4OGdFA0f4xKFQa+964vSzYduyr 26B7HoAc7z58008J4B3ARpokxz4yXzyWJzVWKIwtiz7RaHu5Gjn9WsdEyVaxLPiNgWwR Wg2udQIZsl9Hm00g3IWZ9j3GeHnM/8QdA53N8= 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= Received: by 10.204.8.141 with SMTP id h13mr1208218bkh.64.1304953581776; Mon, 09 May 2011 08:06:21 -0700 (PDT) Received: from [147.32.89.145] (terror.pod.cvut.cz [147.32.89.145]) by mx.google.com with ESMTPS id d25sm1237304bkd.17.2011.05.09.08.06.20 (version=SSLv3 cipher=OTHER); Mon, 09 May 2011 08:06:20 -0700 (PDT) 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: Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter2.kernel.org [140.211.167.43]); Mon, 09 May 2011 15:06:38 +0000 (UTC) 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? 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-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html 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; }