From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751663AbbIGMxs (ORCPT ); Mon, 7 Sep 2015 08:53:48 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:40514 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751010AbbIGMxq (ORCPT ); Mon, 7 Sep 2015 08:53:46 -0400 Date: Mon, 7 Sep 2015 13:53:43 +0100 From: Luis Henriques To: Sergey Senozhatsky Cc: Minchan Kim , Nitin Gupta , Sergey Senozhatsky , linux-kernel@vger.kernel.org Subject: Re: [PATCH] zram: fix possible use after free in zcomp_create() Message-ID: <20150907125343.GG10075@ares> References: <1441622033-8358-1-git-send-email-luis.henriques@canonical.com> <20150907111148.GB27956@swordfish> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20150907111148.GB27956@swordfish> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 07, 2015 at 08:11:48PM +0900, Sergey Senozhatsky wrote: > On (09/07/15 11:33), Luis Henriques wrote: > > zcomp_create() verifies the success of zcomp_strm_{multi,siggle}_create() > > through comp->stream, which can potentially be pointing to memory that was > > freed if these functions returned an error. > > > > good catch. > > we probably better start checking the zcomp_strm_multi_create()/ > zcomp_strm_single_create() status in zcomp_create(); that's much > more obvious and that's why we return it in the first place. > > what do you think? > Yep, that's probably a better solution. Acked-by: Luis Henriques Cheers, -- Luís > --- > > drivers/block/zram/zcomp.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c > index 3456d5a..16bbc8c 100644 > --- a/drivers/block/zram/zcomp.c > +++ b/drivers/block/zram/zcomp.c > @@ -360,6 +360,7 @@ struct zcomp *zcomp_create(const char *compress, int max_strm) > { > struct zcomp *comp; > struct zcomp_backend *backend; > + int ret; > > backend = find_backend(compress); > if (!backend) > @@ -371,10 +372,10 @@ struct zcomp *zcomp_create(const char *compress, int max_strm) > > comp->backend = backend; > if (max_strm > 1) > - zcomp_strm_multi_create(comp, max_strm); > + ret = zcomp_strm_multi_create(comp, max_strm); > else > - zcomp_strm_single_create(comp); > - if (!comp->stream) { > + ret = zcomp_strm_single_create(comp); > + if (ret != 0) { > kfree(comp); > return ERR_PTR(-ENOMEM); > } >