Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756619Ab1F1Gmw (ORCPT ); Tue, 28 Jun 2011 02:42:52 -0400 Received: from cantor2.suse.de ([195.135.220.15]:54393 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756261Ab1F1GkZ (ORCPT ); Tue, 28 Jun 2011 02:40:25 -0400 Date: Tue, 28 Jun 2011 16:40:14 +1000 From: NeilBrown To: Namhyung Kim Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] md/raid5: fix possible NULL pointer dereference in debug routine Message-ID: <20110628164014.4a916b68@notabene.brown> In-Reply-To: <1308891840-5683-1-git-send-email-namhyung@gmail.com> References: <1308891840-5683-1-git-send-email-namhyung@gmail.com> X-Mailer: Claws Mail 3.7.9 (GTK+ 2.22.1; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1816 Lines: 49 On Fri, 24 Jun 2011 14:04:00 +0900 Namhyung Kim wrote: > When I ran dynamic debug, I encountered a NULL pointer dereference > bug in add_stripe_bio(). Prior to second call to pr_debug(), @bi > was reused in order to check whether the request is partial write > or not, and it could lead to set @bi to NULL. > > Since we save original @bi pointer into local variable 'bip', use > it instead of NULL-able @bi. > > Also changed confusing 'bh' to 'bi' in the first message. > > Signed-off-by: Namhyung Kim > --- > drivers/md/raid5.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c > index 82c07fb38961..c814a6075c79 100644 > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -2139,7 +2139,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in > raid5_conf_t *conf = sh->raid_conf; > int firstwrite=0; > > - pr_debug("adding bh b#%llu to stripe s#%llu\n", > + pr_debug("adding bi b#%llu to stripe s#%llu\n", > (unsigned long long)bi->bi_sector, > (unsigned long long)sh->sector); > > @@ -2181,7 +2181,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in > spin_unlock_irq(&conf->device_lock); > > pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n", > - (unsigned long long)bi->bi_sector, > + (unsigned long long)(*bip)->bi_sector, > (unsigned long long)sh->sector, dd_idx); > > if (conf->mddev->bitmap && firstwrite) { Applied, thanks. NeilBrown -- 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/