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From: Jason Wang <jasowang@redhat.com>
Message-ID: <575F7E75.2040805@redhat.com>
Date: Tue, 14 Jun 2016 11:48:05 +0800
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Subject: Re: [Qemu-devel] [PATCH] net: mipsnet: check transmit buffer size
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To: Aurelien Jarno <aurelien@aurel32.net>, Peter Maydell <peter.maydell@linaro.org>
Cc: P J P <ppandit@redhat.com>, Qemu Developers <qemu-devel@nongnu.org>, Li Qiang <liqiang6-s@360.cn>, Prasad J Pandit <pjp@fedoraproject.org>, Leon Alrae <leon.alrae@imgtec.com>



On 2016=E5=B9=B406=E6=9C=8813=E6=97=A5 16:35, Aurelien Jarno wrote:
> On 2016-06-02 10:28, Peter Maydell wrote:
>> On 2 June 2016 at 07:44, P J P <ppandit@redhat.com> wrote:
>>> From: Prasad J Pandit <pjp@fedoraproject.org>
>>>
>>> When processing MIPSnet I/O port write operation, it uses a
>>> transmit buffer tx_buffer[MAX_ETH_FRAME_SIZE=3D1514]. Two indices
>>> 's->tx_written' and 's->tx_count' are used to control data written
>>> to this buffer. If the two were to be equal before writing, it'd
>>> lead to an OOB write access beyond tx_buffer. Add check to avoid it.
>>>
>>> Reported-by: Li Qiang <liqiang6-s@360.cn>
>>> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
>>> ---
>>>   hw/net/mipsnet.c | 10 ++++++----
>>>   1 file changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/hw/net/mipsnet.c b/hw/net/mipsnet.c
>>> index 740cd98..8d5e5bf 100644
>>> --- a/hw/net/mipsnet.c
>>> +++ b/hw/net/mipsnet.c
>>> @@ -158,7 +158,7 @@ static void mipsnet_ioport_write(void *opaque, hw=
addr addr,
>>>       trace_mipsnet_write(addr, val);
>>>       switch (addr) {
>>>       case MIPSNET_TX_DATA_COUNT:
>>> -       s->tx_count =3D (val <=3D MAX_ETH_FRAME_SIZE) ? val : 0;
>>> +        s->tx_count =3D (val < MAX_ETH_FRAME_SIZE) ? val : MAX_ETH_F=
RAME_SIZE;
>>>           s->tx_written =3D 0;
>> This is a behaviour change -- the register will now read
>> back as MAX_ETH_FRAME_SIZE rather than 0 if written with
>> an overlarge value.
>>
>> Do we have any documentation on how this (simulated)
>> device is supposed to behave in this case?
> This device is not supported by the linux kernel for more than 2.5 year=
s
> (since v3.7). Do we want to keep this device in QEMU?
>
> Aurelien
>

Right, so I suggest to remove this from qemu.