From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752048AbdHBX7I (ORCPT ); Wed, 2 Aug 2017 19:59:08 -0400 Received: from mail-pf0-f174.google.com ([209.85.192.174]:32941 "EHLO mail-pf0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751161AbdHBX7H (ORCPT ); Wed, 2 Aug 2017 19:59:07 -0400 Date: Wed, 2 Aug 2017 16:59:05 -0700 From: Matthias Kaehlcke To: Minchan Kim Cc: Doug Anderson , Nitin Gupta , Sergey Senozhatsky , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] zram: Fix buffer size passed to strlcpy() Message-ID: <20170802235905.GI84665@google.com> References: <20170728171243.23374-1-mka@chromium.org> <20170802234437.GD32020@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170802234437.GD32020@bbox> 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 El Thu, Aug 03, 2017 at 08:44:37AM +0900 Minchan Kim ha dit: > Hi Doug, > > On Wed, Aug 02, 2017 at 03:54:32PM -0700, Doug Anderson wrote: > > Hi, > > > > On Fri, Jul 28, 2017 at 10:12 AM, Matthias Kaehlcke wrote: > > > comp_algorithm_store() passes the size of the source buffer to strlcpy() > > > instead of the destination buffer size, fix this. > > > > This was introduced in commit 415403be37e2 ("zram: use crypto api to > > check alg availability"), but probably don't need a "Fixes" since > > there's not really a bug (see below) > > > > > Signed-off-by: Matthias Kaehlcke > > > --- > > > drivers/block/zram/zram_drv.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > index 856d5dc02451..7d2ddffad361 100644 > > > --- a/drivers/block/zram/zram_drv.c > > > +++ b/drivers/block/zram/zram_drv.c > > > @@ -327,7 +327,7 @@ static ssize_t comp_algorithm_store(struct device *dev, > > > return -EBUSY; > > > } > > > > > > - strlcpy(zram->compressor, compressor, sizeof(compressor)); > > > + strlcpy(zram->compressor, compressor, sizeof(zram->compressor)); > > > > As far as I can tell the two sizes are identical. In struct zram: > > > > char compressor[CRYPTO_MAX_ALG_NAME]; > > > > Locally here: > > > > char compressor[CRYPTO_MAX_ALG_NAME]; > > > > ...so there is no bug per say unless there's a hidden "#undef". > > ...but your change does make it a little clearer, plus if someone ever > > changed one of these arrays it would be safer. Thus: > > > > Reviewed-by: Douglas Anderson > > > > > > I suppose another option would be to define the local array based on > > the size of the structure. AKA locally in the function: > > > > char compressor[ARRAY_SIZE(zram->compressor)]; > > > > ...if you did that you could replace the strlcpy() below with a simple > > strcpy() since you'd be guaranteed that there's be enough space. > > ...but I'm probably overthinking it too much. ;-P > > First of all, Thanks for the patch, Matthias. You are correct and you > patch doesn't have any problem. However, I think Doug's suggestion > looks better. Could you mind resending? Sure, I can rework the patch.