Re: [PATCH 1/3] net: ethernet: bcmasp: fix possible OOB write in bcmasp_netfilt_get_all_active()

[Hangyu Hua]

On 7/9/2023 17:44, Paolo Abeni wrote:
> On Wed, 2023-09-06 at 17:21 +0800, Hangyu Hua wrote:
> > rule_locs is allocated in ethtool_get_rxnfc and the size is determined by
> > rule_cnt from user space. So rule_cnt needs to be check before using
> > rule_locs to avoid OOB writing or NULL pointer dereference.
> >
> > Fixes: c5d511c49587 ("net: bcmasp: Add support for wake on net filters")
> > Signed-off-by: Hangyu Hua <hbh25y@xxxxxxxxx>
> > ---
> >   drivers/net/ethernet/broadcom/asp2/bcmasp.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> > index d63d321f3e7b..4df2ca871af8 100644
> > --- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> > +++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> > @@ -535,6 +535,9 @@ void bcmasp_netfilt_get_all_active(struct bcmasp_intf *intf, u32 *rule_locs,
> >   	int j = 0, i;
> >   
> >   	for (i = 0; i < NUM_NET_FILTERS; i++) {
> > +		if (j == *rule_cnt)
> > +			break;
>
> Side note: it's a bit unfortunate/confusing that the drivers can
> arbitrary return  -EMSGSIZE or silently truncate the list. I think it
> would be clearer if we could stick to single behavior - and I'll vote
> for -EMSGSIZE.

I see. I used break directly here beacause this function is defined as
void. But since you mentioned this I will fix this out.

Thanks,
Hangyu

> Cheers,
>
> Paolo