Re: [PATCH v2] md: raid1: fix potential OOB in raid1_remove_disk()

[Song Liu]

On Mon, Jul 24, 2023 at 10:12 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
>
> 在 2023/07/22 15:53, Zhang Shurong 写道:
> > If rddev->raid_disk is greater than mddev->raid_disks, there will be
> > an out-of-bounds in raid1_remove_disk(). We have already found
> > similar reports as follows:
> >
> > 1) commit d17f744e883b ("md-raid10: fix KASAN warning")
> > 2) commit 1ebc2cec0b7d ("dm raid: fix KASAN warning in raid5_remove_disk")
> >
> > Fix this bug by checking whether the "number" variable is
> > valid.
>
> LGTM
>
> Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> >
> > Signed-off-by: Zhang Shurong <zhang_shurong@xxxxxxxxxxx>
> > ---
> > Changes in v2:
> >   - Using conf->raid_disks instead of mddev->raid_disks.
> >
> >   drivers/md/raid1.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> > index dd25832eb045..80aeee63dfb7 100644
> > --- a/drivers/md/raid1.c
> > +++ b/drivers/md/raid1.c
> > @@ -1829,6 +1829,10 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
> >       struct r1conf *conf = mddev->private;
> >       int err = 0;
> >       int number = rdev->raid_disk;
> > +
> > +     if (unlikely(number >= conf->raid_disks))
> > +             goto abort;

We need err = -EINVAL here.

> > +
> >       struct raid1_info *p = conf->mirrors + number;
> >
> >       if (rdev != p->rdev)
> >
>