[PATCH] [next] drm/amdgpu: Replace 1-element array with flexible-array member

* [PATCH] [next] drm/amdgpu: Replace 1-element array with flexible-array member
@ 2022-11-07  9:32 Paulo Miguel Almeida
  2022-11-08 15:59 ` Alex Deucher
  0 siblings, 1 reply; 2+ messages in thread
From: Paulo Miguel Almeida @ 2022-11-07  9:32 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, Pan, Xinhui, David Airlie, Daniel Vetter,
	Paulo Miguel Almeida, Slark Xiao, Rongguang Wei, amd-gfx,
	dri-devel
  Cc: paulo.miguel.almeida.rodenas, linux-kernel, linux-hardening

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_GPIO_PIN_ASSIGNMENT,
_ATOM_DISPLAY_OBJECT_PATH, _ATOM_DISPLAY_OBJECT_PATH_TABLE,
_ATOM_OBJECT_TABLE and refactor the rest of the code accordingly.

Important to mention is that doing a build before/after this patch results
in no functional 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>
---

Binary difference findings:

	Some changes took more than a single line which changed the line
	number parameter passed to the drm_dbg function (which leverages
	kernel's dynamic debugging). Functionally-wise, nothing changed
	after doing a before/after patch build.

Additional one-element arrays to be changed:

	There are more instances of one-element arrays to be changed but
	I will keep patches small so they are easy to review. [and I can
	only dedicate a few hours per day on this :-) ]

---
 .../gpu/drm/amd/display/dc/bios/bios_parser.c | 23 ++++++++++++-------
 drivers/gpu/drm/amd/include/atombios.h        |  8 +++----
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
index 9b8ea6e9a2b9..39dd8b2dc254 100644
--- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
+++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
@@ -138,7 +138,9 @@ static uint8_t get_number_of_objects(struct bios_parser *bp, uint32_t offset)
 
 	uint32_t object_table_offset = bp->object_info_tbl_offset + offset;
 
-	table = GET_IMAGE(ATOM_OBJECT_TABLE, object_table_offset);
+	table = ((ATOM_OBJECT_TABLE *) bios_get_image(&bp->base,
+				object_table_offset,
+				struct_size(table, asObjects, 1)));
 
 	if (!table)
 		return 0;
@@ -166,8 +168,9 @@ static struct graphics_object_id bios_parser_get_connector_id(
 	uint32_t connector_table_offset = bp->object_info_tbl_offset
 		+ le16_to_cpu(bp->object_info_tbl.v1_1->usConnectorObjectTableOffset);
 
-	ATOM_OBJECT_TABLE *tbl =
-		GET_IMAGE(ATOM_OBJECT_TABLE, connector_table_offset);
+	ATOM_OBJECT_TABLE *tbl = ((ATOM_OBJECT_TABLE *) bios_get_image(&bp->base,
+				connector_table_offset,
+				struct_size(tbl, asObjects, 1)));
 
 	if (!tbl) {
 		dm_error("Can't get connector table from atom bios.\n");
@@ -1789,11 +1792,13 @@ static enum bp_result bios_parser_get_gpio_pin_info(
 	if (!DATA_TABLES(GPIO_Pin_LUT))
 		return BP_RESULT_BADBIOSTABLE;
 
-	header = GET_IMAGE(ATOM_GPIO_PIN_LUT, DATA_TABLES(GPIO_Pin_LUT));
+	header = ((ATOM_GPIO_PIN_LUT *) bios_get_image(&bp->base,
+				DATA_TABLES(GPIO_Pin_LUT),
+				struct_size(header, asGPIO_Pin, 1)));
 	if (!header)
 		return BP_RESULT_BADBIOSTABLE;
 
-	if (sizeof(ATOM_COMMON_TABLE_HEADER) + sizeof(ATOM_GPIO_PIN_LUT)
+	if (sizeof(ATOM_COMMON_TABLE_HEADER) + struct_size(header, asGPIO_Pin, 1)
 			> le16_to_cpu(header->sHeader.usStructureSize))
 		return BP_RESULT_BADBIOSTABLE;
 
@@ -1978,7 +1983,8 @@ static ATOM_OBJECT *get_bios_object(struct bios_parser *bp,
 
 	offset += bp->object_info_tbl_offset;
 
-	tbl = GET_IMAGE(ATOM_OBJECT_TABLE, offset);
+	tbl = ((ATOM_OBJECT_TABLE *) bios_get_image(&bp->base, offset,
+				struct_size(tbl, asObjects, 1)));
 	if (!tbl)
 		return NULL;
 
@@ -2709,8 +2715,9 @@ static enum bp_result get_bracket_layout_record(
 
 	genericTableOffset = bp->object_info_tbl_offset +
 		bp->object_info_tbl.v1_3->usMiscObjectTableOffset;
-	object_table = (ATOM_OBJECT_TABLE *)
-		GET_IMAGE(ATOM_OBJECT_TABLE, genericTableOffset);
+	object_table = ((ATOM_OBJECT_TABLE *) bios_get_image(&bp->base,
+				genericTableOffset,
+				struct_size(object_table, asObjects, 1)));
 	if (!object_table)
 		return BP_RESULT_FAILURE;
 
diff --git a/drivers/gpu/drm/amd/include/atombios.h b/drivers/gpu/drm/amd/include/atombios.h
index b5b1d073f8e2..55ae93c1e365 100644
--- a/drivers/gpu/drm/amd/include/atombios.h
+++ b/drivers/gpu/drm/amd/include/atombios.h
@@ -4386,7 +4386,7 @@ typedef struct _ATOM_GPIO_PIN_ASSIGNMENT
 typedef struct _ATOM_GPIO_PIN_LUT
 {
   ATOM_COMMON_TABLE_HEADER  sHeader;
-  ATOM_GPIO_PIN_ASSIGNMENT   asGPIO_Pin[1];
+  ATOM_GPIO_PIN_ASSIGNMENT   asGPIO_Pin[];
 }ATOM_GPIO_PIN_LUT;
 
 /****************************************************************************/
@@ -4513,7 +4513,7 @@ 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
@@ -4530,7 +4530,7 @@ 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;
 
 typedef struct _ATOM_OBJECT                                //each object has this structure
@@ -4545,7 +4545,7 @@ 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
-- 
2.37.3


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