netdev - Re: [PATCH 8/9] bpf: Check address length before reading address family

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAADnVQLh+fJciux3bMSure6fmw_krQ6OVeJzwhf3JEeOb4kYFQ@mail.gmail.com>
Date:   Fri, 12 Apr 2019 09:19:53 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Network Development <netdev@...r.kernel.org>,
        Andrey Ignatov <rdna@...com>
Subject: Re: [PATCH 8/9] bpf: Check address length before reading address family

On Fri, Apr 12, 2019 at 3:56 AM Tetsuo Handa
<penguin-kernel@...ove.sakura.ne.jp> wrote:
>
> KMSAN will complain if valid address length passed to bpf_bind() is
> shorter than sizeof("struct sockaddr"->sa_family) bytes.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> ---
>  net/core/filter.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 41f633cf4fc1..b9089fda4367 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4458,6 +4458,8 @@ BPF_CALL_3(bpf_bind, struct bpf_sock_addr_kern *, ctx, struct sockaddr *, addr,
>          * Only binding to IP is supported.
>          */
>         err = -EINVAL;
> +       if (addr_len < offsetofend(struct sockaddr, sa_family))
> +               return err;

the verifier will check that addr_len is not zero,
but it can be one byte, so it's a good check.
Thanks!

>         if (addr->sa_family == AF_INET) {
>                 if (addr_len < sizeof(struct sockaddr_in))
>                         return err;
> --
> 2.16.5
>