From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: md: raid10: fix use-after-free of bio Date: Mon, 30 Jul 2007 18:44:37 +1000 Message-ID: <18093.42229.134557.618117@notabene.brown> References: <1185547583.2663.10.camel@c64> <20070728235519.1edc6ccb.akpm@linux-foundation.org> <1185783111.2684.15.camel@c64> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Maik Hampel on Monday July 30 Sender: linux-raid-owner@vger.kernel.org To: Maik Hampel Cc: Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-raid@vger.kernel.org" List-Id: linux-raid.ids On Monday July 30, m.hampel@gmx.de wrote: > > > > Surely we just leaked that bio if (mirror == -1)? > > > > better: > > > > --- a/drivers/md/raid10.c~md-raid10-fix-use-after-free-of-bio > > +++ a/drivers/md/raid10.c > > @@ -1534,7 +1534,6 @@ static void raid10d(mddev_t *mddev) > > bio = r10_bio->devs[r10_bio->read_slot].bio; > > r10_bio->devs[r10_bio->read_slot].bio = > > mddev->ro ? IO_BLOCKED : NULL; > > - bio_put(bio); > > mirror = read_balance(conf, r10_bio); > > if (mirror == -1) { > > printk(KERN_ALERT "raid10: %s: unrecoverable I/O" > > @@ -1542,8 +1541,10 @@ static void raid10d(mddev_t *mddev) > > bdevname(bio->bi_bdev,b), > > (unsigned long long)r10_bio->sector); > > raid_end_bio_io(r10_bio); > > + bio_put(bio); > raid_end_bio_io() calls put_all_bios(), which does a bio_put() to > corresponding r10_bio->devs[i]. So this looks like redundant code for > me. Yes, but note above that this bio for this slot has been set to 'NULL', so put_all_bios won't find anything to call bio_put on. Thanks, NeilBrown > > } else { > > const int do_sync = bio_sync(r10_bio->master_bio); > > + bio_put(bio); > > rdev = conf->mirrors[mirror].rdev; > > if (printk_ratelimit()) > > printk(KERN_ERR "raid10: %s: redirecting sector %llu to" > > Regards, > Maik Hampel >