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

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Message-ID: <f0fb2ffbde15b2939ed76545b549bdcd33b92ae8.camel@redhat.com>
Date:   Mon, 16 May 2022 15:14:22 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Pavel Begunkov <asml.silence@...il.com>, netdev@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 03/10] udp/ipv6: prioritise the ip6 path
 over ip4 checks

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@...il.com>
> ---
>  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:

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

Paolo