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

From: Paulo Miguel Almeida
Date: Fri Oct 28 2022 - 01:41:40 EST


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/239
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 [1]

Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@xxxxxxxxx>
---
drivers/gpu/drm/radeon/atombios.h | 2 +-
drivers/gpu/drm/radeon/radeon_atombios.c | 12 ++++++++----
2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios.h b/drivers/gpu/drm/radeon/atombios.h
index da35a970fcc0..235e59b547a1 100644
--- a/drivers/gpu/drm/radeon/atombios.h
+++ b/drivers/gpu/drm/radeon/atombios.h
@@ -3615,7 +3615,7 @@ typedef struct _ATOM_FAKE_EDID_PATCH_RECORD
{
UCHAR ucRecordType;
UCHAR ucFakeEDIDLength;
- 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
diff --git a/drivers/gpu/drm/radeon/radeon_atombios.c b/drivers/gpu/drm/radeon/radeon_atombios.c
index 204127bad89c..48de2521f253 100644
--- a/drivers/gpu/drm/radeon/radeon_atombios.c
+++ b/drivers/gpu/drm/radeon/radeon_atombios.c
@@ -1716,7 +1716,7 @@ struct radeon_encoder_atom_dig *radeon_atombios_get_lvds_info(struct
max((int)EDID_LENGTH, (int)fake_edid_record->ucFakeEDIDLength);
edid = kmalloc(edid_size, GFP_KERNEL);
if (edid) {
- memcpy((u8 *)edid, (u8 *)&fake_edid_record->ucFakeEDIDString[0],
+ memcpy((u8 *)edid, (u8 *)fake_edid_record->ucFakeEDIDString,
fake_edid_record->ucFakeEDIDLength);

if (drm_edid_is_valid(edid)) {
@@ -1725,10 +1725,14 @@ struct radeon_encoder_atom_dig *radeon_atombios_get_lvds_info(struct
} 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(*fake_edid_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;
--
2.37.3