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From:   Alexander Aring <aahringo@redhat.com>
Date:   Tue, 23 Aug 2022 08:22:13 -0400
Message-ID: <CAK-6q+hf27dY9d-FyAh2GtA_zG5J4kkHEX2Qj38Rac_PH63bQg@mail.gmail.com>
Subject: Re: [PATCH] net/ieee802154: fix uninit value bug in dgram_sendmsg
To:     Stefan Schmidt <stefan@datenfreihafen.org>
Cc:     Haimin Zhang <tcs.kernel@gmail.com>,
        Alexander Aring <alex.aring@gmail.com>,
        "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 23, 2022 at 5:42 AM Stefan Schmidt
<stefan@datenfreihafen.org> wrote:
>
> Hello.
>
> On 22.08.22 09:19, Haimin Zhang 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.
> >
> > This length is specified by msg->msg_namelen. Function
> > ieee802154_addr_from_sa is called by dgram_sendmsg, which use
> > msg->msg_name as struct sockaddr_ieee802154* and read it, that will
> > eventually lead to uninit value read. So we should check the length of
> > msg->msg_name is not less than sizeof(struct sockaddr_ieee802154)
> > before entering the ieee802154_addr_from_sa.
> >
> > Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
>
>
> This patch has been applied to the wpan tree and will be
> part of the next pull request to net. Thanks!

For me this patch is buggy or at least it is questionable how to deal
with the size of ieee802154_addr_sa here.

There should be a helper to calculate the size which depends on the
addr_type field. It is not required to send the last 6 bytes if
addr_type is IEEE802154_ADDR_SHORT.
Nitpick is that we should check in the beginning of that function.

- Alex