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SubjectRe: md: raid10: fix use-after-free of bio
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
>
-
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