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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Fri, 9 Dec 2022 18:16:34 -0500
Message-ID: <CADnq5_NOyyLetx+wUtYL4f7ETHzVFAw_JnbGXGh5G1KYbUH3Zg@mail.gmail.com>
Subject: Re: [PATCH] [next] drm/radeon: Replace 1-element arrays with
 flexible-array members
To:     Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
Cc:     Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>, amd-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
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Applied.  Thanks!

Alex

On Fri, Dec 9, 2022 at 3:24 AM Paulo Miguel Almeida
<paulo.miguel.almeida.rodenas@gmail.com> wrote:
>
> One-element arrays are deprecated, and we are replacing them with
> flexible array members instead. So, replace one-element array with
> flexible-array member in structs _ATOM_DISPLAY_OBJECT_PATH,
> _ATOM_DISPLAY_OBJECT_PATH_TABLE, _ATOM_OBJECT_TABLE, GOP_VBIOS_CONTENT
> _ATOM_GPIO_VOLTAGE_OBJECT_V3 and refactor the rest of the code accordingly.
>
> It's worth mentioning that doing a build before/after this patch
> results in no binary output differences.
>
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [1].
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/239
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 [1]
>
> Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
> ---
> Notes for the maintainer:
>
> - These are all fake-flexible arrays with references in source code for
>   the radeon driver. Given the way they are used, no change to *.c files
>   were required.
> ---
>  drivers/gpu/drm/radeon/atombios.h | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/atombios.h b/drivers/gpu/drm/radeon/atombios.h
> index 235e59b547a1..8a6621f1e82c 100644
> --- a/drivers/gpu/drm/radeon/atombios.h
> +++ b/drivers/gpu/drm/radeon/atombios.h
> @@ -4020,7 +4020,7 @@ typedef struct  _ATOM_DISPLAY_OBJECT_PATH
>    USHORT    usSize;                                        //the size of ATOM_DISPLAY_OBJECT_PATH
>    USHORT    usConnObjectId;                                //Connector Object ID
>    USHORT    usGPUObjectId;                                 //GPU ID
> -  USHORT    usGraphicObjIds[1];                             //1st Encoder Obj source from GPU to last Graphic Obj destinate to connector.
> +  USHORT    usGraphicObjIds[];                             //1st Encoder Obj source from GPU to last Graphic Obj destinate to connector.
>  }ATOM_DISPLAY_OBJECT_PATH;
>
>  typedef struct  _ATOM_DISPLAY_EXTERNAL_OBJECT_PATH
> @@ -4037,7 +4037,7 @@ typedef struct _ATOM_DISPLAY_OBJECT_PATH_TABLE
>    UCHAR                           ucNumOfDispPath;
>    UCHAR                           ucVersion;
>    UCHAR                           ucPadding[2];
> -  ATOM_DISPLAY_OBJECT_PATH        asDispPath[1];
> +  ATOM_DISPLAY_OBJECT_PATH        asDispPath[];
>  }ATOM_DISPLAY_OBJECT_PATH_TABLE;
>
>
> @@ -4053,7 +4053,7 @@ typedef struct _ATOM_OBJECT_TABLE                         //Above 4 object table
>  {
>    UCHAR               ucNumberOfObjects;
>    UCHAR               ucPadding[3];
> -  ATOM_OBJECT         asObjects[1];
> +  ATOM_OBJECT         asObjects[];
>  }ATOM_OBJECT_TABLE;
>
>  typedef struct _ATOM_SRC_DST_TABLE_FOR_ONE_OBJECT         //usSrcDstTableOffset pointing to this structure
> @@ -4615,7 +4615,7 @@ typedef struct  _ATOM_GPIO_VOLTAGE_OBJECT_V3
>     UCHAR    ucPhaseDelay;                // phase delay in unit of micro second
>     UCHAR    ucReserved;
>     ULONG    ulGpioMaskVal;               // GPIO Mask value
> -   VOLTAGE_LUT_ENTRY_V2 asVolGpioLut[1];
> +   VOLTAGE_LUT_ENTRY_V2 asVolGpioLut[];
>  }ATOM_GPIO_VOLTAGE_OBJECT_V3;
>
>  typedef struct  _ATOM_LEAKAGE_VOLTAGE_OBJECT_V3
> @@ -7964,7 +7964,7 @@ typedef struct {
>
>  typedef struct {
>    VFCT_IMAGE_HEADER    VbiosHeader;
> -  UCHAR        VbiosContent[1];
> +  UCHAR        VbiosContent[];
>  }GOP_VBIOS_CONTENT;
>
>  typedef struct {
> --
> 2.38.1
>