ASoC: Intel: Skylake: Fix struct definition

The kernel is globally removing the ambiguous 0-length and 1-element
arrays in favor of flexible arrays, so that we can gain both compile-time
and run-time array bounds checking[1]. In this instance, struct
skl_cpr_cfg contains struct skl_cpr_gtw_cfg, which defined "config_data"
as a 1-element array.

However, case present in sound/soc/intel/skylake/skl-topology.h is not a
simple one as the structure takes part in IPC communication. Apparently
original definition missed one field, which while not used by AudioDSP
firmware when there is no additional data, is still expected to be part
of an IPC message. Currently this works because of how 'config_data' is
declared: 'config_data[1]'. Now when one replaces it with a flexible
array there would be one field missing. Update struct declaration to fix
this.

Reported-by: Sasa Ostrouska <[email protected]>
Link: https://lore.kernel.org/all/CALFERdwvq5day_sbDfiUsMSZCQu9HG8-SBpOZDNPeMdZGog6XA@mail.gmail.com/
Cc: Pierre-Louis Bossart <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Peter Ujfalusi <[email protected]>
Cc: Bard Liao <[email protected]>
Cc: Ranjani Sridharan <[email protected]>
Cc: Kai Vehmanen <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: "Gustavo A. R. Silva" <[email protected]>
Cc: [email protected]
CC: Kees Cook <[email protected]>
Reviewed-by: Cezary Rojewski <[email protected]>
Signed-off-by: Amadeusz Sławiński <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: Amadeusz Sławiński

sound/soc/intel/skylake/skl-messages.c

@@ -549,7 +549,7 @@ static void skl_copy_copier_caps(struct skl_module_cfg *mconfig,
 	if (mconfig->formats_config[SKL_PARAM_INIT].caps_size == 0)
 		return;
 
-	memcpy(cpr_mconfig->gtw_cfg.config_data,
+	memcpy(&cpr_mconfig->gtw_cfg.config_data,
 			mconfig->formats_config[SKL_PARAM_INIT].caps,
 			mconfig->formats_config[SKL_PARAM_INIT].caps_size);
 

sound/soc/intel/skylake/skl-topology.h

@@ -115,7 +115,10 @@ struct skl_cpr_gtw_cfg {
 	u32 dma_buffer_size;
 	u32 config_length;
 	/* not mandatory; required only for DMIC/I2S */
-	u32 config_data[1];
+	struct {
+		u32 gtw_attrs;
+		u32 data[];
+	} config_data;
 } __packed;
 
 struct skl_dma_control {