Re: [PATCH 9/9] udpv6: Check address length before reading address family

[Song Liu <songliubraving@fb.com>]

> On Apr 12, 2019, at 3:56 AM, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
> 
> KMSAN will complain if valid address length passed to udpv6_pre_connect()
> is shorter than sizeof("struct sockaddr"->sa_family) bytes.
> 
> (This patch is bogus if it is guaranteed that udpv6_pre_connect() is
> always called after checking "struct sockaddr"->sa_family. In that case,
> we want a comment why we don't need to check valid address length here.)
> 
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

Looks good. 

Acked-by: Song Liu <songliubraving@fb.com>


> ---
> net/ipv6/udp.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index d538fafaf4a9..2464fba569b4 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1045,6 +1045,8 @@ static void udp_v6_flush_pending_frames(struct sock *sk)
> static int udpv6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
> 			     int addr_len)
> {
> +	if (addr_len < offsetofend(struct sockaddr, sa_family))
> +		return -EINVAL;
> 	/* The following checks are replicated from __ip6_datagram_connect()
> 	 * and intended to prevent BPF program called below from accessing
> 	 * bytes that are out of the bound specified by user in addr_len.
> -- 
> 2.16.5
>