drm/i915/bios: Make copies of VBT data blocks

Make a copy of each VBT data block with a guaranteed minimum
size. The extra (if any) will just be left zeroed.

This means we don't have to worry about going out of bounds
when accessing any of the structure members. Otherwise that
could easliy happen if we simply get the version check wrong,
or if the VBT is broken/malicious.

v2: Don't do arithmetic between bdb header and copy
    of the LFP data block (Jani)
v3: Make all the copies up front
v4: Only WARN about min_size==0 if we found the block
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220406133817.30652-1-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_bios.c

@@ -88,7 +88,7 @@ static u32 get_blocksize(const void *block_data)
 }
 
 static const void *
-find_section(const void *_bdb, enum bdb_block_id section_id)
+find_raw_section(const void *_bdb, enum bdb_block_id section_id)
 {
 	const struct bdb_header *bdb = _bdb;
 	const u8 *base = _bdb;
@@ -118,6 +118,124 @@ find_section(const void *_bdb, enum bdb_block_id section_id)
 	return NULL;
 }
 
+/*
+ * Offset from the start of BDB to the start of the
+ * block data (just past the block header).
+ */
+static u32 block_offset(const void *bdb, enum bdb_block_id section_id)
+{
+	const void *block;
+
+	block = find_raw_section(bdb, section_id);
+	if (!block)
+		return 0;
+
+	return block - bdb;
+}
+
+struct bdb_block_entry {
+	struct list_head node;
+	enum bdb_block_id section_id;
+	u8 data[];
+};
+
+static const void *
+find_section(struct drm_i915_private *i915,
+	     enum bdb_block_id section_id)
+{
+	struct bdb_block_entry *entry;
+
+	list_for_each_entry(entry, &i915->vbt.bdb_blocks, node) {
+		if (entry->section_id == section_id)
+			return entry->data + 3;
+	}
+
+	return NULL;
+}
+
+static const struct {
+	enum bdb_block_id section_id;
+	size_t min_size;
+} bdb_blocks[] = {
+	{ .section_id = BDB_GENERAL_FEATURES,
+	  .min_size = sizeof(struct bdb_general_features), },
+	{ .section_id = BDB_GENERAL_DEFINITIONS,
+	  .min_size = sizeof(struct bdb_general_definitions), },
+	{ .section_id = BDB_PSR,
+	  .min_size = sizeof(struct bdb_psr), },
+	{ .section_id = BDB_DRIVER_FEATURES,
+	  .min_size = sizeof(struct bdb_driver_features), },
+	{ .section_id = BDB_SDVO_LVDS_OPTIONS,
+	  .min_size = sizeof(struct bdb_sdvo_lvds_options), },
+	{ .section_id = BDB_SDVO_PANEL_DTDS,
+	  .min_size = sizeof(struct bdb_sdvo_panel_dtds), },
+	{ .section_id = BDB_EDP,
+	  .min_size = sizeof(struct bdb_edp), },
+	{ .section_id = BDB_LVDS_OPTIONS,
+	  .min_size = sizeof(struct bdb_lvds_options), },
+	{ .section_id = BDB_LVDS_LFP_DATA_PTRS,
+	  .min_size = sizeof(struct bdb_lvds_lfp_data_ptrs), },
+	{ .section_id = BDB_LVDS_LFP_DATA,
+	  .min_size = sizeof(struct bdb_lvds_lfp_data), },
+	{ .section_id = BDB_LVDS_BACKLIGHT,
+	  .min_size = sizeof(struct bdb_lfp_backlight_data), },
+	{ .section_id = BDB_LFP_POWER,
+	  .min_size = sizeof(struct bdb_lfp_power), },
+	{ .section_id = BDB_MIPI_CONFIG,
+	  .min_size = sizeof(struct bdb_mipi_config), },
+	{ .section_id = BDB_MIPI_SEQUENCE,
+	  .min_size = sizeof(struct bdb_mipi_sequence) },
+	{ .section_id = BDB_COMPRESSION_PARAMETERS,
+	  .min_size = sizeof(struct bdb_compression_parameters), },
+	{ .section_id = BDB_GENERIC_DTD,
+	  .min_size = sizeof(struct bdb_generic_dtd), },
+};
+
+static void
+init_bdb_block(struct drm_i915_private *i915,
+	       const void *bdb, enum bdb_block_id section_id,
+	       size_t min_size)
+{
+	struct bdb_block_entry *entry;
+	const void *block;
+	size_t block_size;
+
+	block = find_raw_section(bdb, section_id);
+	if (!block)
+		return;
+
+	drm_WARN(&i915->drm, min_size == 0,
+		 "Block %d min_size is zero\n", section_id);
+
+	block_size = get_blocksize(block);
+
+	entry = kzalloc(struct_size(entry, data, max(min_size, block_size) + 3),
+			GFP_KERNEL);
+	if (!entry)
+		return;
+
+	entry->section_id = section_id;
+	memcpy(entry->data, block - 3, block_size + 3);
+
+	drm_dbg_kms(&i915->drm, "Found BDB block %d (size %zu, min size %zu)\n",
+		    section_id, block_size, min_size);
+
+	list_add_tail(&entry->node, &i915->vbt.bdb_blocks);
+}
+
+static void init_bdb_blocks(struct drm_i915_private *i915,
+			    const void *bdb)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(bdb_blocks); i++) {
+		enum bdb_block_id section_id = bdb_blocks[i].section_id;
+		size_t min_size = bdb_blocks[i].min_size;
+
+		init_bdb_block(i915, bdb, section_id, min_size);
+	}
+}
+
 static void
 fill_detail_timing_data(struct drm_display_mode *panel_fixed_mode,
 			const struct lvds_dvo_timing *dvo_timing)
@@ -199,7 +317,7 @@ get_lvds_fp_timing(const struct bdb_header *bdb,
 		   const struct bdb_lvds_lfp_data_ptrs *ptrs,
 		   int index)
 {
-	size_t data_ofs = (const u8 *)data - (const u8 *)bdb;
+	size_t data_ofs = block_offset(bdb, BDB_LVDS_LFP_DATA);
 	u16 data_size = ((const u16 *)data)[-1]; /* stored in header */
 	size_t ofs;
 
@@ -214,15 +332,14 @@ get_lvds_fp_timing(const struct bdb_header *bdb,
 
 /* Parse general panel options */
 static void
-parse_panel_options(struct drm_i915_private *i915,
-		    const struct bdb_header *bdb)
+parse_panel_options(struct drm_i915_private *i915)
 {
 	const struct bdb_lvds_options *lvds_options;
 	int panel_type;
 	int drrs_mode;
 	int ret;
 
-	lvds_options = find_section(bdb, BDB_LVDS_OPTIONS);
+	lvds_options = find_section(i915, BDB_LVDS_OPTIONS);
 	if (!lvds_options)
 		return;
 
@@ -285,11 +402,11 @@ parse_lfp_panel_dtd(struct drm_i915_private *i915,
 	struct drm_display_mode *panel_fixed_mode;
 	int panel_type = i915->vbt.panel_type;
 
-	lvds_lfp_data = find_section(bdb, BDB_LVDS_LFP_DATA);
+	lvds_lfp_data = find_section(i915, BDB_LVDS_LFP_DATA);
 	if (!lvds_lfp_data)
 		return;
 
-	lvds_lfp_data_ptrs = find_section(bdb, BDB_LVDS_LFP_DATA_PTRS);
+	lvds_lfp_data_ptrs = find_section(i915, BDB_LVDS_LFP_DATA_PTRS);
 	if (!lvds_lfp_data_ptrs)
 		return;
 
@@ -325,15 +442,14 @@ parse_lfp_panel_dtd(struct drm_i915_private *i915,
 }
 
 static void
-parse_generic_dtd(struct drm_i915_private *i915,
-		  const struct bdb_header *bdb)
+parse_generic_dtd(struct drm_i915_private *i915)
 {
 	const struct bdb_generic_dtd *generic_dtd;
 	const struct generic_dtd_entry *dtd;
 	struct drm_display_mode *panel_fixed_mode;
 	int num_dtd;
 
-	generic_dtd = find_section(bdb, BDB_GENERIC_DTD);
+	generic_dtd = find_section(i915, BDB_GENERIC_DTD);
 	if (!generic_dtd)
 		return;
 
@@ -416,21 +532,20 @@ parse_panel_dtd(struct drm_i915_private *i915,
 	 * back to trying the old LFP block if that fails.
 	 */
 	if (i915->vbt.version >= 229)
-		parse_generic_dtd(i915, bdb);
+		parse_generic_dtd(i915);
 	if (!i915->vbt.lfp_lvds_vbt_mode)
 		parse_lfp_panel_dtd(i915, bdb);
 }
 
 static void
-parse_lfp_backlight(struct drm_i915_private *i915,
-		    const struct bdb_header *bdb)
+parse_lfp_backlight(struct drm_i915_private *i915)
 {
 	const struct bdb_lfp_backlight_data *backlight_data;
 	const struct lfp_backlight_data_entry *entry;
 	int panel_type = i915->vbt.panel_type;
 	u16 level;
 
-	backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT);
+	backlight_data = find_section(i915, BDB_LVDS_BACKLIGHT);
 	if (!backlight_data)
 		return;
 
@@ -514,8 +629,7 @@ parse_lfp_backlight(struct drm_i915_private *i915,
 
 /* Try to find sdvo panel data */
 static void
-parse_sdvo_panel_data(struct drm_i915_private *i915,
-		      const struct bdb_header *bdb)
+parse_sdvo_panel_data(struct drm_i915_private *i915)
 {
 	const struct bdb_sdvo_panel_dtds *dtds;
 	struct drm_display_mode *panel_fixed_mode;
@@ -531,14 +645,14 @@ parse_sdvo_panel_data(struct drm_i915_private *i915,
 	if (index == -1) {
 		const struct bdb_sdvo_lvds_options *sdvo_lvds_options;
 
-		sdvo_lvds_options = find_section(bdb, BDB_SDVO_LVDS_OPTIONS);
+		sdvo_lvds_options = find_section(i915, BDB_SDVO_LVDS_OPTIONS);
 		if (!sdvo_lvds_options)
 			return;
 
 		index = sdvo_lvds_options->panel_type;
 	}
 
-	dtds = find_section(bdb, BDB_SDVO_PANEL_DTDS);
+	dtds = find_section(i915, BDB_SDVO_PANEL_DTDS);
 	if (!dtds)
 		return;
 
@@ -570,12 +684,11 @@ static int intel_bios_ssc_frequency(struct drm_i915_private *i915,
 }
 
 static void
-parse_general_features(struct drm_i915_private *i915,
-		       const struct bdb_header *bdb)
+parse_general_features(struct drm_i915_private *i915)
 {
 	const struct bdb_general_features *general;
 
-	general = find_section(bdb, BDB_GENERAL_FEATURES);
+	general = find_section(i915, BDB_GENERAL_FEATURES);
 	if (!general)
 		return;
 
@@ -695,12 +808,11 @@ parse_sdvo_device_mapping(struct drm_i915_private *i915)
 }
 
 static void
-parse_driver_features(struct drm_i915_private *i915,
-		      const struct bdb_header *bdb)
+parse_driver_features(struct drm_i915_private *i915)
 {
 	const struct bdb_driver_features *driver;
 
-	driver = find_section(bdb, BDB_DRIVER_FEATURES);
+	driver = find_section(i915, BDB_DRIVER_FEATURES);
 	if (!driver)
 		return;
 
@@ -747,8 +859,7 @@ parse_driver_features(struct drm_i915_private *i915,
 }
 
 static void
-parse_power_conservation_features(struct drm_i915_private *i915,
-				  const struct bdb_header *bdb)
+parse_power_conservation_features(struct drm_i915_private *i915)
 {
 	const struct bdb_lfp_power *power;
 	u8 panel_type = i915->vbt.panel_type;
@@ -756,7 +867,7 @@ parse_power_conservation_features(struct drm_i915_private *i915,
 	if (i915->vbt.version < 228)
 		return;
 
-	power = find_section(bdb, BDB_LFP_POWER);
+	power = find_section(i915, BDB_LFP_POWER);
 	if (!power)
 		return;
 
@@ -776,14 +887,14 @@ parse_power_conservation_features(struct drm_i915_private *i915,
 }
 
 static void
-parse_edp(struct drm_i915_private *i915, const struct bdb_header *bdb)
+parse_edp(struct drm_i915_private *i915)
 {
 	const struct bdb_edp *edp;
 	const struct edp_power_seq *edp_pps;
 	const struct edp_fast_link_params *edp_link_params;
 	int panel_type = i915->vbt.panel_type;
 
-	edp = find_section(bdb, BDB_EDP);
+	edp = find_section(i915, BDB_EDP);
 	if (!edp)
 		return;
 
@@ -894,13 +1005,13 @@ parse_edp(struct drm_i915_private *i915, const struct bdb_header *bdb)
 }
 
 static void
-parse_psr(struct drm_i915_private *i915, const struct bdb_header *bdb)
+parse_psr(struct drm_i915_private *i915)
 {
 	const struct bdb_psr *psr;
 	const struct psr_table *psr_table;
 	int panel_type = i915->vbt.panel_type;
 
-	psr = find_section(bdb, BDB_PSR);
+	psr = find_section(i915, BDB_PSR);
 	if (!psr) {
 		drm_dbg_kms(&i915->drm, "No PSR BDB found.\n");
 		return;
@@ -1034,8 +1145,7 @@ static void parse_dsi_backlight_ports(struct drm_i915_private *i915,
 }
 
 static void
-parse_mipi_config(struct drm_i915_private *i915,
-		  const struct bdb_header *bdb)
+parse_mipi_config(struct drm_i915_private *i915)
 {
 	const struct bdb_mipi_config *start;
 	const struct mipi_config *config;
@@ -1058,7 +1168,7 @@ parse_mipi_config(struct drm_i915_private *i915,
 	/* Parse #52 for panel index used from panel_type already
 	 * parsed
 	 */
-	start = find_section(bdb, BDB_MIPI_CONFIG);
+	start = find_section(i915, BDB_MIPI_CONFIG);
 	if (!start) {
 		drm_dbg_kms(&i915->drm, "No MIPI config BDB found");
 		return;
@@ -1354,8 +1464,7 @@ static void fixup_mipi_sequences(struct drm_i915_private *i915)
 }
 
 static void
-parse_mipi_sequence(struct drm_i915_private *i915,
-		    const struct bdb_header *bdb)
+parse_mipi_sequence(struct drm_i915_private *i915)
 {
 	int panel_type = i915->vbt.panel_type;
 	const struct bdb_mipi_sequence *sequence;
@@ -1368,7 +1477,7 @@ parse_mipi_sequence(struct drm_i915_private *i915,
 	if (i915->vbt.dsi.panel_id != MIPI_DSI_GENERIC_PANEL_ID)
 		return;
 
-	sequence = find_section(bdb, BDB_MIPI_SEQUENCE);
+	sequence = find_section(i915, BDB_MIPI_SEQUENCE);
 	if (!sequence) {
 		drm_dbg_kms(&i915->drm,
 			    "No MIPI Sequence found, parsing complete\n");
@@ -1439,8 +1548,7 @@ parse_mipi_sequence(struct drm_i915_private *i915,
 }
 
 static void
-parse_compression_parameters(struct drm_i915_private *i915,
-			     const struct bdb_header *bdb)
+parse_compression_parameters(struct drm_i915_private *i915)
 {
 	const struct bdb_compression_parameters *params;
 	struct intel_bios_encoder_data *devdata;
@@ -1451,7 +1559,7 @@ parse_compression_parameters(struct drm_i915_private *i915,
 	if (i915->vbt.version < 198)
 		return;
 
-	params = find_section(bdb, BDB_COMPRESSION_PARAMETERS);
+	params = find_section(i915, BDB_COMPRESSION_PARAMETERS);
 	if (params) {
 		/* Sanity checks */
 		if (params->entry_size != sizeof(params->data[0])) {
@@ -2086,8 +2194,7 @@ static void parse_ddi_ports(struct drm_i915_private *i915)
 }
 
 static void
-parse_general_definitions(struct drm_i915_private *i915,
-			  const struct bdb_header *bdb)
+parse_general_definitions(struct drm_i915_private *i915)
 {
 	const struct bdb_general_definitions *defs;
 	struct intel_bios_encoder_data *devdata;
@@ -2097,7 +2204,7 @@ parse_general_definitions(struct drm_i915_private *i915,
 	u16 block_size;
 	int bus_pin;
 
-	defs = find_section(bdb, BDB_GENERAL_DEFINITIONS);
+	defs = find_section(i915, BDB_GENERAL_DEFINITIONS);
 	if (!defs) {
 		drm_dbg_kms(&i915->drm,
 			    "No general definition block is found, no devices defined.\n");
@@ -2466,6 +2573,7 @@ void intel_bios_init(struct drm_i915_private *i915)
 	const struct bdb_header *bdb;
 
 	INIT_LIST_HEAD(&i915->vbt.display_devices);
+	INIT_LIST_HEAD(&i915->vbt.bdb_blocks);
 
 	if (!HAS_DISPLAY(i915)) {
 		drm_dbg_kms(&i915->drm,
@@ -2499,22 +2607,24 @@ void intel_bios_init(struct drm_i915_private *i915)
 		    "VBT signature \"%.*s\", BDB version %d\n",
 		    (int)sizeof(vbt->signature), vbt->signature, i915->vbt.version);
 
+	init_bdb_blocks(i915, bdb);
+
 	/* Grab useful general definitions */
-	parse_general_features(i915, bdb);
-	parse_general_definitions(i915, bdb);
-	parse_panel_options(i915, bdb);
+	parse_general_features(i915);
+	parse_general_definitions(i915);
+	parse_panel_options(i915);
 	parse_panel_dtd(i915, bdb);
-	parse_lfp_backlight(i915, bdb);
-	parse_sdvo_panel_data(i915, bdb);
-	parse_driver_features(i915, bdb);
-	parse_power_conservation_features(i915, bdb);
-	parse_edp(i915, bdb);
-	parse_psr(i915, bdb);
-	parse_mipi_config(i915, bdb);
-	parse_mipi_sequence(i915, bdb);
+	parse_lfp_backlight(i915);
+	parse_sdvo_panel_data(i915);
+	parse_driver_features(i915);
+	parse_power_conservation_features(i915);
+	parse_edp(i915);
+	parse_psr(i915);
+	parse_mipi_config(i915);
+	parse_mipi_sequence(i915);
 
 	/* Depends on child device list */
-	parse_compression_parameters(i915, bdb);
+	parse_compression_parameters(i915);
 
 out:
 	if (!vbt) {
@@ -2536,14 +2646,20 @@ void intel_bios_init(struct drm_i915_private *i915)
  */
 void intel_bios_driver_remove(struct drm_i915_private *i915)
 {
-	struct intel_bios_encoder_data *devdata, *n;
+	struct intel_bios_encoder_data *devdata, *nd;
+	struct bdb_block_entry *entry, *ne;
 
-	list_for_each_entry_safe(devdata, n, &i915->vbt.display_devices, node) {
+	list_for_each_entry_safe(devdata, nd, &i915->vbt.display_devices, node) {
 		list_del(&devdata->node);
 		kfree(devdata->dsc);
 		kfree(devdata);
 	}
 
+	list_for_each_entry_safe(entry, ne, &i915->vbt.bdb_blocks, node) {
+		list_del(&entry->node);
+		kfree(entry);
+	}
+
 	kfree(i915->vbt.sdvo_lvds_vbt_mode);
 	i915->vbt.sdvo_lvds_vbt_mode = NULL;
 	kfree(i915->vbt.lfp_lvds_vbt_mode);

drivers/gpu/drm/i915/i915_drv.h

@@ -379,6 +379,7 @@ struct intel_vbt_data {
 	int crt_ddc_pin;
 
 	struct list_head display_devices;
+	struct list_head bdb_blocks;
 
 	struct intel_bios_encoder_data *ports[I915_MAX_PORTS]; /* Non-NULL if port present. */
 	struct sdvo_device_mapping sdvo_mappings[2];