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

Christian König
2022-10-28T07:18:52Z

Am 28.10.22 um 07:10 schrieb Paulo Miguel Almeida:
> 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.
>
> 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]

I'm not sure if that's a good idea. We had multiple attempts to refactor
this now and it always caused a regression.

Additional to that the header in question came from our BIOS team and
isn't following Linux styles in general.

Alex what do you think?

Regards,
Christian.

>
> Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
> ---
> drivers/gpu/drm/amd/amdgpu/atombios_encoders.c | 10 +++++++---
> drivers/gpu/drm/amd/include/atombios.h | 2 +-
> 2 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> index 6be9ac2b9c5b..6b5abf1249db 100644
> --- a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> +++ b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> @@ -2079,10 +2079,14 @@ amdgpu_atombios_encoder_get_lcd_info(struct amdgpu_encoder *encoder)
> } else
> kfree(edid);
> }
> +
> + record += struct_size(fake_edid_record,
> + ucFakeEDIDString,
> + fake_edid_record->ucFakeEDIDLength);
> + } else {
> + /* empty fake edid record must be 3 bytes long */
> + record += sizeof(ATOM_FAKE_EDID_PATCH_RECORD) + 1;
> }
> - record += fake_edid_record->ucFakeEDIDLength ?
> - fake_edid_record->ucFakeEDIDLength + 2 :
> - sizeof(ATOM_FAKE_EDID_PATCH_RECORD);
> 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