netdev - Re: [PATCH net-next] net: Fix incorrect address comparison when searching for a bind2 bucket

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Date:   Tue, 27 Sep 2022 20:49:55 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Martin KaFai Lau <kafai@...com>
Cc:     netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        kernel-team <kernel-team@...com>,
        Paolo Abeni <pabeni@...hat.com>,
        Joanne Koong <joannelkoong@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Martin KaFai Lau <martin.lau@...nel.org>
Subject: Re: [PATCH net-next] net: Fix incorrect address comparison when
 searching for a bind2 bucket

On Mon, Sep 26, 2022 at 5:25 PM Martin KaFai Lau <kafai@...com> wrote:
>
> From: Martin KaFai Lau <martin.lau@...nel.org>
>
> The v6_rcv_saddr and rcv_saddr are inside a union in the
> 'struct inet_bind2_bucket'.  When searching a bucket by following the
> bhash2 hashtable chain, eg. inet_bind2_bucket_match, it is only using
> the sk->sk_family and there is no way to check if the inet_bind2_bucket
> has a v6 or v4 address in the union.  This leads to an uninit-value
> KMSAN report in [0] and also potentially incorrect matches.

I do not see the KMSAN report, is it missing from this changelog ?

Thanks.


>
> This patch fixes it by adding a family member to the inet_bind2_bucket
> and then tests 'sk->sk_family != tb->family' before matching
> the sk's address to the tb's address.


>
> Cc: Joanne Koong <joannelkoong@...il.com>
> Cc: Alexander Potapenko <glider@...gle.com>
> Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address")
> Signed-off-by: Martin KaFai Lau <martin.lau@...nel.org>
> ---
>  include/net/inet_hashtables.h |  3 +++
>  net/ipv4/inet_hashtables.c    | 10 ++++++++++
>  2 files changed, 13 insertions(+)
>
> diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
> index 9121ccab1fa1..3af1e927247d 100644
> --- a/include/net/inet_hashtables.h
> +++ b/include/net/inet_hashtables.h
> @@ -95,6 +95,9 @@ struct inet_bind2_bucket {
>         possible_net_t          ib_net;
>         int                     l3mdev;
>         unsigned short          port;
> +#if IS_ENABLED(CONFIG_IPV6)
> +       unsigned short          family;
> +#endif
>         union {
>  #if IS_ENABLED(CONFIG_IPV6)
>                 struct in6_addr         v6_rcv_saddr;
> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> index 74e64aad5114..49db8c597eea 100644
> --- a/net/ipv4/inet_hashtables.c
> +++ b/net/ipv4/inet_hashtables.c
> @@ -109,6 +109,7 @@ static void inet_bind2_bucket_init(struct inet_bind2_bucket *tb,
>         tb->l3mdev    = l3mdev;
>         tb->port      = port;
>  #if IS_ENABLED(CONFIG_IPV6)
> +       tb->family    = sk->sk_family;
>         if (sk->sk_family == AF_INET6)
>                 tb->v6_rcv_saddr = sk->sk_v6_rcv_saddr;
>         else
> @@ -146,6 +147,9 @@ static bool inet_bind2_bucket_addr_match(const struct inet_bind2_bucket *tb2,
>                                          const struct sock *sk)
>  {
>  #if IS_ENABLED(CONFIG_IPV6)
> +       if (sk->sk_family != tb2->family)
> +               return false;
> +
>         if (sk->sk_family == AF_INET6)
>                 return ipv6_addr_equal(&tb2->v6_rcv_saddr,
>                                        &sk->sk_v6_rcv_saddr);
> @@ -791,6 +795,9 @@ static bool inet_bind2_bucket_match(const struct inet_bind2_bucket *tb,
>                                     int l3mdev, const struct sock *sk)
>  {
>  #if IS_ENABLED(CONFIG_IPV6)
> +       if (sk->sk_family != tb->family)
> +               return false;
> +
>         if (sk->sk_family == AF_INET6)
>                 return net_eq(ib2_net(tb), net) && tb->port == port &&
>                         tb->l3mdev == l3mdev &&
> @@ -807,6 +814,9 @@ bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const
>  #if IS_ENABLED(CONFIG_IPV6)
>         struct in6_addr addr_any = {};
>
> +       if (sk->sk_family != tb->family)
> +               return false;
> +
>         if (sk->sk_family == AF_INET6)
>                 return net_eq(ib2_net(tb), net) && tb->port == port &&
>                         tb->l3mdev == l3mdev &&
> --
> 2.30.2
>