Re: [PATCH net-next v3 03/10] udp/ipv6: prioritise the ip6 path over ip4 checks

[Pavel Begunkov]

On 5/16/22 14:14, Paolo Abeni wrote:
> On Fri, 2022-05-13 at 16:26 +0100, Pavel Begunkov wrote:
> > For AF_INET6 sockets we care the most about ipv6 but not ip4 mappings as
> > it's requires some extra hops anyway. Take AF_INET6 case from the address
> > parsing switch and add an explicit path for it. It removes some extra
> > ifs from the path and removes the switch overhead.
> >
> > Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
> > ---
> >   net/ipv6/udp.c | 37 +++++++++++++++++--------------------
> >   1 file changed, 17 insertions(+), 20 deletions(-)
> >
> > diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> > index 85bff1252f5c..e0b1bea998ce 100644
> > --- a/net/ipv6/udp.c
> > +++ b/net/ipv6/udp.c
> > @@ -1360,30 +1360,27 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> >   
> >   	/* destination address check */
> >   	if (sin6) {
> > -		if (addr_len < offsetof(struct sockaddr, sa_data))
> > -			return -EINVAL;
> > +		if (addr_len < SIN6_LEN_RFC2133 || sin6->sin6_family != AF_INET6) {
> > +			if (addr_len < offsetof(struct sockaddr, sa_data))
> > +				return -EINVAL;
>
> I think you can't access 'sin6->sin6_family' before validating the
> socket address len, that is before doing:

Paolo, thanks for reviewing it!


sin6_family is protected by

if (addr_len < SIN6_LEN_RFC2133 ...)

on the previous line. I can add a BUILD_BUG_ON() if that
would be more reassuring.


> if (addr_len < offsetof(struct sockaddr, sa_data))

--
Pavel Begunkov