Re: [PATCH v2 1/4] md/raid10: fix slab-out-of-bounds in md_bitmap_get_counter

[Li Nan]

在 2023/5/13 9:05, Song Liu 写道:
> On Fri, May 5, 2023 at 6:24 PM <linan666@xxxxxxxxxxxxxxx> wrote:
> > From: Li Nan <linan122@xxxxxxxxxx>
> >
> > If we write a large number to md/bitmap_set_bits, md_bitmap_checkpage()
> > will return -EINVAL because "page >= bitmap->pages", but the return value
> > was not checked immediately in md_bitmap_get_counter() in order to set
> > *blocks value and slab-out-of-bounds occurs.
> >
> > Return directly if err is -EINVAL.
> >
> > Fixes: ef4256733506 ("md/bitmap: optimise scanning of empty bitmaps.")
> > Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
> > Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> > ---
> >   drivers/md/md-bitmap.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> > index 920bb68156d2..0b41ef422da7 100644
> > --- a/drivers/md/md-bitmap.c
> > +++ b/drivers/md/md-bitmap.c
> > @@ -1388,6 +1388,8 @@ __acquires(bitmap->lock)
> >          int err;
> >
> >          err = md_bitmap_checkpage(bitmap, page, create, 0);
> > +       if (err == -EINVAL)
> > +               return NULL;
>
> This logic is error prone. Since we are on it, let's fix it better.
> Specifically, we can move "page >= bitmap->pages" check out

I will check out it in v3.

> of md_bitmap_checkpage(). (and fix the call site in md_bitmap_resize
> for clustered md).

In md_bitmap_resize(), incoming parameters "page < bitmap->counts.page" 
and do not have this problem.


> Also, could you please add a mdadm test for this issue?

It's my pleasure.

> Thanks,
> Song
>
> >          if (bitmap->bp[page].hijacked ||
> >              bitmap->bp[page].map == NULL)
> > --
> > 2.31.1
> .

Thanks for your suggesion.

--
Thanks,
Nan