Re: [v2 PATCH bpf-next 1/2] bpf: Check percpu map value size first

[Tao Chen]

在 2024/9/10 04:17, Andrii Nakryiko 写道:
> On Mon, Sep 9, 2024 at 12:14 AM Tao Chen <chen.dylane@xxxxxxxxx> wrote:
> > Percpu map is often used, but the map value size limit often ignored,
> > like issue: https://github.com/iovisor/bcc/issues/2519. Actually,
> > percpu map value size is bound by PCPU_MIN_UNIT_SIZE, so we
> > can check the value size whether it exceeds PCPU_MIN_UNIT_SIZE first,
> > like percpu map of local_storage. Maybe the error message seems clearer
> > compared with "cannot allocate memory".
> >
> > Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx>
> > Signed-off-by: jinke han <jinkehan@xxxxxxxxxxxxxx>
>
> names in SOB should be capitalized

Hi Andrii，thank you for your attention, i will change it.

> the check is useful, so:
>
> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
>
> > ---
> >   kernel/bpf/arraymap.c | 3 +++
> >   kernel/bpf/hashtab.c  | 3 +++
> >   2 files changed, 6 insertions(+)
> >
> > diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
> > index a43e62e2a8bb..79660e3fca4c 100644
> > --- a/kernel/bpf/arraymap.c
> > +++ b/kernel/bpf/arraymap.c
> > @@ -73,6 +73,9 @@ int array_map_alloc_check(union bpf_attr *attr)
> >          /* avoid overflow on round_up(map->value_size) */
> >          if (attr->value_size > INT_MAX)
> >                  return -E2BIG;
> > +       /* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
> > +       if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
> > +               return -E2BIG;
> >
> >          return 0;
> >   }
> > diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> > index 45c7195b65ba..b14b87463ee0 100644
> > --- a/kernel/bpf/hashtab.c
> > +++ b/kernel/bpf/hashtab.c
> > @@ -462,6 +462,9 @@ static int htab_map_alloc_check(union bpf_attr *attr)
> >                   * kmalloc-able later in htab_map_update_elem()
> >                   */
> >                  return -E2BIG;
> > +       /* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
> > +       if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
> > +               return -E2BIG;
> >
> >          return 0;
> >   }
> > --
> > 2.25.1


--
Best Regards
Dylane Chen