From: Hans Verkuil <hverkuil@xs4all.nl>
To: n179911 <n179911@gmail.com>
Cc: linux-media@vger.kernel.org
Subject: Re: Question about implementation of __qbuf_dmabuf() in videobuf2-core.c
Date: Mon, 05 May 2014 12:19:29 +0200 [thread overview]
Message-ID: <536765B1.3050207@xs4all.nl> (raw)
In-Reply-To: <CAKZjMP14q0YTu11hJuQoRoOYihWw5Y63qGAoMUfGpL=2=ouG4g@mail.gmail.com>
On 04/29/2014 07:27 PM, n179911 wrote:
> Hi,
>
> Is there a work around for this bug without upgrading to 3.16 kernel?
>
> Is it safe to manually set the length to be data_offset + size + 1 to make sure
>
> planes[plane].length is greater than planes[plane].data_offset +
> q->plane_sizes[plane]?
Yes, that should be safe. However, if you are building the kernel yourself, then
I would recommend just fixing the kernel instead of working around it elsewhere.
Regards,
Hans
>
> Thank you.
>
> On Wed, Apr 23, 2014 at 12:24 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
>> On 04/23/2014 02:18 AM, n179911 wrote:
>>> In __qbuf_dmabuf(), it check the length and size of the buffer being
>>> queued, like this:
>>> http://lxr.free-electrons.com/source/drivers/media/v4l2-core/videobuf2-core.c#L1158
>>>
>>> My question is why the range check is liked this:
>>>
>>> 1158 if (planes[plane].length < planes[plane].data_offset +
>>> 1159 q->plane_sizes[plane]) {
>>
>> It's a bug. It should be:
>>
>> if (planes[plane].length < q->plane_sizes[plane]) {
>>
>> This has been fixed in our upstream code and will appear in 3.16.
>>
>> Regards,
>>
>> Hans
>>
>>> .....
>>>
>>> Isn't planes[plane].length + planes[plane].data_offset equals to
>>> q->plane_sizes[plane]?
>>>
>>> So the check should be?
>>> if (planes[plane].length < q->plane_sizes[plane] - planes[plane].data_offset)
>>>
>>> Please tell me what am I missing?
>>>
>>> Thank you
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-media" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>
>>
prev parent reply other threads:[~2014-05-05 10:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-23 0:18 Question about implementation of __qbuf_dmabuf() in videobuf2-core.c n179911
2014-04-23 7:24 ` Hans Verkuil
2014-04-29 17:27 ` n179911
2014-05-05 10:19 ` Hans Verkuil [this message]
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