Re: [PATCH RFC 3/5] rtnetlink: do_setlink: Use sockaddr_storage
From: Kees Cook
Date: Mon Dec 16 2024 - 20:52:47 EST
On Tue, Nov 05, 2024 at 11:59:49AM +0100, Eric Dumazet wrote:
>
> On 11/4/24 11:25 PM, Kees Cook wrote:
> > Instead of a heap allocation use a stack allocated sockaddr_storage to
> > support arbitrary length addr_len value (but bounds check it against the
> > maximum address length).
> >
> > Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
> > ---
> > net/core/rtnetlink.c | 12 ++++--------
> > 1 file changed, 4 insertions(+), 8 deletions(-)
> >
> > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> > index f0a520987085..eddd10b74f06 100644
> > --- a/net/core/rtnetlink.c
> > +++ b/net/core/rtnetlink.c
> > @@ -2839,21 +2839,17 @@ static int do_setlink(const struct sk_buff *skb,
> > }
> > if (tb[IFLA_ADDRESS]) {
> > - struct sockaddr *sa;
> > - int len;
> > + struct sockaddr_storage addr;
> > + struct sockaddr *sa = (struct sockaddr *)&addr;
>
> We already use too much stack space.
I'm finally coming back to this. I was over-thinking: this only calls
dev_set_mac_address_user() so it really is a true struct sockaddr.
> Please move addr into struct rtnl_newlink_tbs ?
I couldn't figure out how that was meant to work -- I didn't see a
struct rtnl_newlink_tbs instance near this routine.
Regardless, I can just tweak the length and leave it heap allocated.
-Kees
--
Kees Cook