From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maik Hampel Subject: Re: md: raid10: fix use-after-free of bio Date: Mon, 30 Jul 2007 10:11:51 +0200 Message-ID: <1185783111.2684.15.camel@c64> References: <1185547583.2663.10.camel@c64> <20070728235519.1edc6ccb.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20070728235519.1edc6ccb.akpm@linux-foundation.org> Sender: linux-raid-owner@vger.kernel.org To: Andrew Morton Cc: Neil Brown , "linux-kernel@vger.kernel.org" , "linux-raid@vger.kernel.org" List-Id: linux-raid.ids Am Samstag, den 28.07.2007, 23:55 -0700 schrieb Andrew Morton: > On Fri, 27 Jul 2007 16:46:23 +0200 Maik Hampel wrote: > > > In case of read errors raid10d tries to print a nice error message, > > unfortunately using data from an already put bio. > > > > Signed-off-by: Maik Hampel > > > > diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c > > index f730a14..ea1b3e3 100644 > > --- a/drivers/md/raid10.c > > +++ b/drivers/md/raid10.c > > @@ -1557,7 +1557,6 @@ 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" > > @@ -1567,6 +1566,7 @@ static void raid10d(mddev_t *mddev) > > raid_end_bio_io(r10_bio); > > } 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" > > > > > > 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. > } 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