[EXT] Re: [PATCH v2 1/1] apps: cam: kms_sink: Verify colorSpace presence before dereference

[Antoine Bouyer]

On 17/12/2024 17:46, Laurent Pinchart wrote:

> Caution: This is an external email. Please take care when clicking links or opening attachments. When in doubt, report the message using the 'Report this email' button
>
>
> On Tue, Dec 17, 2024 at 04:23:27PM +0000, Kieran Bingham wrote:
>> Quoting Antoine Bouyer (2024-12-17 14:02:39)
>>> During configuration stage, kms_sink doesn't check optional colorSpace
>>> parameter is valid while dereferencing it. Then it leads to a crash
>>> with below signature if parameter is not defined:
>>>
>>>    /opt/fsl-imx-internal-xwayland/6.12-styhead/sysroots/armv8a-poky-linux/usr/include/c++/14.2.0/optional:48
>>>    2: constexpr const _Tp& std::_Optional_base_impl<_Tp, _Dp>::_M_get() const [with _Tp = libcamera::ColorSp
>>>    ace; _Dp = std::_Optional_base<libcamera::ColorSpace, true, true>]: Assertion 'this->_M_is_engaged()' fai
>>>    led.
>>>    Aborted (core dumped)
>>>
>>> This behavior is confirmed in the "operator->" page:
>>>   (https://en.cppreference.com/w/cpp/utility/optional/operator*)
>>>
>>> "This operator does not check whether the optional contains a value!"
>>>
>>> This crash is observed with styhead's gcc compiler (version 14.2.0),
>>> while it was not with previous scarthgap's gcc compiler (version 13.2.0).
>>>
>>> Use has_value() as a fix to make sure this property exists and prevent
>>> crash.
>>>
>>> Fixes: 6d7ddace5278 ("cam: Add KMS sink class")
>>> Signed-off-by: Antoine Bouyer<antoine.bouyer at nxp.com>
>>> Reviewed-by: Kieran Bingham<kieran.bingham at ideasonboard.com>
>> Thanks for the updates that I suggested, however I'm weary that perhaps
>> Laurent was suggesting this /shouldn't/ be possible to happen and should
>> be fixed in the pipeline handler? (and perhaps enforced?, and maybe
>> guaranteed to be set to RAW if unknown?)
>>
>> We could perhaps have a common path in the configuration that sets RAW
>> when the pipeline handler didn't set it ? Or maybe we enforce it must be
>> set by lc-compliance or such...
> Let's see first, Antoine, which pipeline handler have you encountered
> this issue with ?

This is with imx8-isi pipeline.
Actually I was thinking about such approach initially, then changed to has_value() fix
because of "optional" flag.

>
>>> ---
>>>   src/apps/cam/kms_sink.cpp | 3 ++-
>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/src/apps/cam/kms_sink.cpp b/src/apps/cam/kms_sink.cpp
>>> index 672c985..8f3b867 100644
>>> --- a/src/apps/cam/kms_sink.cpp
>>> +++ b/src/apps/cam/kms_sink.cpp
>>> @@ -153,7 +153,8 @@ int KMSSink::configure(const libcamera::CameraConfiguration &config)
>>>          colorEncoding_ = std::nullopt;
>>>          colorRange_ = std::nullopt;
>>>
>>> -       if (cfg.colorSpace->ycbcrEncoding == libcamera::ColorSpace::YcbcrEncoding::None)
>>> +       if (!cfg.colorSpace.has_value() ||
>>> +           cfg.colorSpace->ycbcrEncoding == libcamera::ColorSpace::YcbcrEncoding::None)
>>>                  return 0;
>>>
>>>          /*
> --
> Regards,
>
> Laurent Pinchart

Best regards

Antoine
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.libcamera.org/pipermail/libcamera-devel/attachments/20241217/616b50be/attachment.htm>