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Date: Tue, 28 Jul 2020 18:04:20 -0500
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: "Winkler, Tomas" <tomas.winkler@...el.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "Usyskin, Alexander" <alexander.usyskin@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Gustavo A . R . Silva" <gustavoars@...nel.org>
Subject: Re: [char-misc-next] Revert "mei: hdcp: Replace one-element array
with flexible-array member"
Tomas,
Please, see some comments below...
On 7/28/20 17:29, Winkler, Tomas wrote:
>>>>>
>>>>> Hi Tomas,
>>>>>
>>>>> On 7/28/20 16:41, Tomas Winkler wrote:
>>>>>> Greg please revert, this commit it changes size of struct
>>>>>> wired_cmd_repeater_auth_stream_req_in, this is not what firmware
>>>>>> is expecting.
>>>>>
>>>>> Could you elaborate on what's the firmware expecting, exactly?
>>>> struct wired_cmd_repeater_auth_stream_req_in {
>>>> - struct hdcp2_streamid_type streams[1];
>>>> + struct hdcp2_streamid_type streams[];
>>>> }
>>>>
>>>> But then you have, which you haven't changed to + 1 byte =
>>>> mei_cldev_send(cldev, (u8 *)&verify_mprime_in,
>>>> sizeof(verify_mprime_in));
>>>>
I don't think the fix for this is to add 1 byte, if any, it seems
to be sizeof(*data->streams), or sizeof(struct hdcp2_streamid_type)
what needs to be added.
But it might be better to code something like this, instead:
diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
index e6c3dc595617..7fe63c915548 100644
--- a/drivers/misc/mei/hdcp/mei_hdcp.c
+++ b/drivers/misc/mei/hdcp/mei_hdcp.c
@@ -572,12 +572,12 @@ static int mei_hdcp_verify_mprime(struct device *dev,
HDCP_2_2_MPRIME_LEN);
drm_hdcp_cpu_to_be24(verify_mprime_in.seq_num_m, data->seq_num_m);
memcpy(verify_mprime_in.streams, data->streams,
- (data->k * sizeof(struct hdcp2_streamid_type)));
+ (data->k * sizeof(*data->streams)));
verify_mprime_in.k = cpu_to_be16(data->k);
byte = mei_cldev_send(cldev, (u8 *)&verify_mprime_in,
- sizeof(verify_mprime_in));
+ struct_size(&verify_mprime_in, streams, data->k));
if (byte < 0) {
dev_dbg(dev, "mei_cldev_send failed. %zd\n", byte);
return byte;
struct_size(&verify_mprime_in, streams, data->k) will give us the size, in bytes,
of struct wired_cmd_repeater_auth_stream_req_in plus the size in bytes for
the streams[] flexible-array, which is determined by struct hdcp2_streamid_type and
data->k.
What do you think?
See more comments below...
>>>
>>> I see, this is the kind of feedback I need from people that knows the
>>> code better. Thanks!
>>>
>>>> But that's not the major point. Point is that we should be able to
>>>> review and test the code before it is merged. You haven't run it, right?
>>>> There is MAINTAINERS file for a reason.
>>>>
>>>
>>> I'm using this command:
>>>
>>> $ scripts/get_maintainer.pl --nokeywords --nogit --nogit-fallback
>>>
>>> and this is the output for both files:
>>>
>>> $ scripts/get_maintainer.pl --nokeywords --nogit --nogit-fallback
>>> drivers/misc/mei/hdcp/mei_hdcp.c Arnd Bergmann <arnd@...db.de>
>>> (supporter:CHAR and MISC DRIVERS) Greg Kroah-Hartman
>>> <gregkh@...uxfoundation.org> (supporter:CHAR and MISC DRIVERS) linux-
>>> kernel@...r.kernel.org (open list) $ scripts/get_maintainer.pl
>>> --nokeywords -- nogit --nogit-fallback
>>> drivers/misc/mei/hdcp/mei_hdcp.h Arnd Bergmann <arnd@...db.de>
>>> (supporter:CHAR and MISC DRIVERS) Greg Kroah-Hartman
>>> <gregkh@...uxfoundation.org> (supporter:CHAR and MISC DRIVERS) linux-
>>> kernel@...r.kernel.org (open list)
>>
>>
>>> For some reason you don't appear on the list above. Do you see
>>> anything wrong with the command I'm running to get the maintainers and
>> lists?
>>
>> Not sure, it should be caught by drivers/misc/mei/* ?
>> Maybe it is not recursive? Need to check the script, frankly I usually check this
>> manually.
>>
>> INTEL MANAGEMENT ENGINE (mei)
>> M: Tomas Winkler <tomas.winkler@...el.com>
>> L: linux-kernel@...r.kernel.org
>> S: Supported
>> F: Documentation/driver-api/mei/*
>> F: drivers/misc/mei/*
>> F: drivers/watchdog/mei_wdt.c
>> F: include/linux/mei_cl_bus.h
>> F: include/uapi/linux/mei.h
>> F: samples/mei/*
>>
>
> It's not recursive, when I add drivers/misc/mei/hdcp/* . It works correctly
> I will post a patch.
>
Great. I'm glad we got to the root cause of this issue. :)
Thanks
--
Gustavo
> Thanks
> Tomas
>
>
>>
>>>
>>> Thanks
>>> --
>>> Gustavo
>>>
>>>>>
>>>>>> I really do not appreciate that the code is bypassing driver
>>>>>> maintaner review, I think this is a minimum we can ask for, this
>>>>>> is not for a first time.
>>>>>>
>>>>>> This reverts commit c56967d674e361ebe716e66992e3c5332b25ac1f.
>>>>>>
>>>>>> Cc: Gustavo A. R. Silva <gustavoars@...nel.org>
>>>>>> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
>>>>>> ---
>>>>>> drivers/misc/mei/hdcp/mei_hdcp.c | 2 +-
>>>>>> drivers/misc/mei/hdcp/mei_hdcp.h | 2 +-
>>>>>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c
>>>>>> b/drivers/misc/mei/hdcp/mei_hdcp.c
>>>>>> index d1d3e025ca0e..e6c3dc595617 100644
>>>>>> --- a/drivers/misc/mei/hdcp/mei_hdcp.c
>>>>>> +++ b/drivers/misc/mei/hdcp/mei_hdcp.c
>>>>>> @@ -572,7 +572,7 @@ static int mei_hdcp_verify_mprime(struct
>>>>>> device
>>>>> *dev,
>>>>>> HDCP_2_2_MPRIME_LEN);
>>>>>> drm_hdcp_cpu_to_be24(verify_mprime_in.seq_num_m, data-
>>> seq_num_m);
>>>>>> memcpy(verify_mprime_in.streams, data->streams,
>>>>>> - array_size(data->k, sizeof(*data->streams)));
>>>>>> + (data->k * sizeof(struct hdcp2_streamid_type)));
>>>>>>
>>>>>> verify_mprime_in.k = cpu_to_be16(data->k);
>>>>>>
>>>>>> diff --git a/drivers/misc/mei/hdcp/mei_hdcp.h
>>>>>> b/drivers/misc/mei/hdcp/mei_hdcp.h
>>>>>> index 834757f5e072..18ffc773fa18 100644
>>>>>> --- a/drivers/misc/mei/hdcp/mei_hdcp.h
>>>>>> +++ b/drivers/misc/mei/hdcp/mei_hdcp.h
>>>>>> @@ -358,7 +358,7 @@ struct
>> wired_cmd_repeater_auth_stream_req_in
>>> {
>>>>>> u8
>>>>> seq_num_m[HDCP_2_2_SEQ_NUM_LEN];
>>>>>> u8 m_prime[HDCP_2_2_MPRIME_LEN];
>>>>>> __be16 k;
>>>>>> - struct hdcp2_streamid_type streams[];
>>>>>> + struct hdcp2_streamid_type streams[1];
>>>>>> } __packed;
>>>>>>
>>>>>> struct wired_cmd_repeater_auth_stream_req_out {
>>>>>>
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