Re: [PATCH v2] [next] drm/amdgpu: Replace one-element array with flexible-array member

Alex Deucher
2022-11-02T16:17:34Z

Applied. Thanks!

Alex

On Fri, Oct 28, 2022 at 9:31 PM 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 struct _ATOM_FAKE_EDID_PATCH_RECORD and
> refactor the rest of the code accordingly.
>
> Important to mention is 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/238
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 [1]
>
> Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
> ---
> Changelog:
>
> v2: no binary output differences patch; report binary changes findings
> on commit log. Res: Kees Cook
> v1: https://lore.kernel.org/lkml/Y1tkWdwPUp+UdpM0@mail.google.com/
> ---
> drivers/gpu/drm/amd/amdgpu/atombios_encoders.c | 7 +++++--
> drivers/gpu/drm/amd/include/atombios.h | 2 +-
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> index 6be9ac2b9c5b..18ae9433e463 100644
> --- a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> +++ b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> @@ -2081,8 +2081,11 @@ amdgpu_atombios_encoder_get_lcd_info(struct amdgpu_encoder *encoder)
> }
> }
> record += fake_edid_record->ucFakeEDIDLength ?
> - fake_edid_record->ucFakeEDIDLength + 2 :
> - sizeof(ATOM_FAKE_EDID_PATCH_RECORD);
> + struct_size(fake_edid_record,
> + ucFakeEDIDString,
> + fake_edid_record->ucFakeEDIDLength) :
> + /* empty fake edid record must be 3 bytes long */
> + sizeof(ATOM_FAKE_EDID_PATCH_RECORD) + 1;
> break;
> case LCD_PANEL_RESOLUTION_RECORD_TYPE:
> panel_res_record = (ATOM_PANEL_RESOLUTION_PATCH_RECORD *)record;
> diff --git a/drivers/gpu/drm/amd/include/atombios.h b/drivers/gpu/drm/amd/include/atombios.h
> index 15943bc21bc5..b5b1d073f8e2 100644
> --- a/drivers/gpu/drm/amd/include/atombios.h
> +++ b/drivers/gpu/drm/amd/include/atombios.h
> @@ -4107,7 +4107,7 @@ typedef struct _ATOM_FAKE_EDID_PATCH_RECORD
> {
> UCHAR ucRecordType;
> UCHAR ucFakeEDIDLength; // = 128 means EDID length is 128 bytes, otherwise the EDID length = ucFakeEDIDLength*128
> - UCHAR ucFakeEDIDString[1]; // This actually has ucFakeEdidLength elements.
> + UCHAR ucFakeEDIDString[]; // This actually has ucFakeEdidLength elements.
> } ATOM_FAKE_EDID_PATCH_RECORD;
>
> typedef struct _ATOM_PANEL_RESOLUTION_PATCH_RECORD
> --
> 2.37.3
>