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Message-ID: <85f66a3a-95fa-5aaa-def0-998bf3f5139f@datenfreihafen.org>
Date:   Mon, 29 Aug 2022 11:08:42 +0200
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Subject: Re: [PATCH] net/ieee802154: fix uninit value bug in dgram_sendmsg
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To:     Alexander Aring <aahringo@redhat.com>
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>
References: <20220822071902.3419042-1-tcs_kernel@tencent.com>
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 <CAK-6q+hf27dY9d-FyAh2GtA_zG5J4kkHEX2Qj38Rac_PH63bQg@mail.gmail.com>
From:   Stefan Schmidt <stefan@datenfreihafen.org>
In-Reply-To: <CAK-6q+hf27dY9d-FyAh2GtA_zG5J4kkHEX2Qj38Rac_PH63bQg@mail.gmail.com>
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Hello Alex.

On 23.08.22 14:22, Alexander Aring wrote:
> 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.

You are right. I completely missed this. Thanks for spotting!

> 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.

Haimin, in ieee802154 we could have two different sizes for 
ieee802154_addr_sa depending on the addr_type. We have short and 
extended addresses.

Could you please rework this patch to take this into account as Alex 
suggested?

I reverted your original patch from my tree.

regards
Stefan Schmidt