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From:   Alexander Aring <aahringo@redhat.com>
Date:   Wed, 7 Sep 2022 22:02:14 -0400
Message-ID: <CAK-6q+iGfyKdcXRy5Qq+71D=BE2NbXPNSjx6YELr1HO0RYYk-g@mail.gmail.com>
Subject: Re: [PATCH V2] net/ieee802154: fix uninit value bug in dgram_sendmsg
To:     Haimin Zhang <tcs.kernel@gmail.com>
Cc:     Alexander Aring <alex.aring@gmail.com>,
        Stefan Schmidt <stefan@datenfreihafen.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        linux-wpan - ML <linux-wpan@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Haimin Zhang <tcs_kernel@tencent.com>
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Hi,

On Tue, Aug 30, 2022 at 3:03 AM Haimin Zhang <tcs.kernel@gmail.com> wrote:
>
> There is uninit value bug in dgram_sendmsg function in
> net/ieee802154/socket.c when the length of valid data pointed by the
> msg->msg_name isn't verified.
>
> We should check the msg_namelen is not less than struct
> sockaddr_ieee802154 when addr_type is SHORT before calling
> ieee802154_addr_from_sa. So we define IEEE802154_MIN_NAMELEN.
> And in function ieee802154_addr_from_sa, when
> addr_type is LONG, we check msg_namelen is not less than
> sizeof(struct sockaddr_ieee802154). Meanwhile we check in the
> beginning of function dgram_sendmsg.
>

There exists also an IEEE802154_ADDR_NONE addr_type.

We need to first check that space is there to evaluate the addr_type.

If it's NONE, ignore hwaddr or short address. If it's SHORT or hwaddr
check if they have space for it, if it's something completely
different return -EINVAL.

There are still missing bits and I would recommend introducing a
helper function to do this "kind" of more complex check. This patch
spreads different checks around by checking on IEEE802154_MIN_NAMELEN
(which isn't correct, because NONE) and then requires another check by
calling ieee802154_addr_from_sa() and checking the return code.

- Alex