ASoC: tas2781: check the validity of prm_no/cfg_no

Add additional checks for program/config numbers to avoid loading from
invalid addresses.

If prm_no/cfg_no is negative, skip uploading program/config.

The tas2781-hda driver caused a NULL pointer dereference after loading
module, and before first runtime_suspend.

the state was:
tas_priv->cur_conf = -1;
tas_priv->tasdevice[i].cur_conf = 0;
program = &(tas_fmw->programs[-1]);

BUG: kernel NULL pointer dereference, address: 0000000000000010
Call Trace:
 <TASK>
 ? __die+0x23/0x70
 ? page_fault_oops+0x171/0x4e0
 ? vprintk_emit+0x175/0x2b0
 ? exc_page_fault+0x7f/0x180
 ? asm_exc_page_fault+0x26/0x30
 ? tasdevice_load_block_kernel+0x21/0x310 [snd_soc_tas2781_fmwlib]
 tasdevice_select_tuningprm_cfg+0x268/0x3a0 [snd_soc_tas2781_fmwlib]
 tasdevice_tuning_switch+0x69/0x710 [snd_soc_tas2781_fmwlib]
 tas2781_hda_playback_hook+0xd4/0x110 [snd_hda_scodec_tas2781_i2c]

Fixes: 915f5ead ("ASoC: tas2781: firmware lib")
CC:  <stable@vger.kernel.org>
Signed-off-by: Gergo Koteles <soyer@irl.hu>
Link: https://msgid.link/r/523780155bfdca9bc0acd39efc79ed039454818d.1702591356.git.soyer@irl.huSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/tas2781-fmwlib.c

@@ -2189,11 +2189,11 @@ int tasdevice_select_tuningprm_cfg(void *context, int prm_no,
 		goto out;
 	}
 
-	conf = &(tas_fmw->configs[cfg_no]);
 	for (i = 0, prog_status = 0; i < tas_priv->ndev; i++) {
 		if (cfg_info[rca_conf_no]->active_dev & (1 << i)) {
-			if (tas_priv->tasdevice[i].cur_prog != prm_no
-				|| tas_priv->force_fwload_status) {
+			if (prm_no >= 0
+				&& (tas_priv->tasdevice[i].cur_prog != prm_no
+				|| tas_priv->force_fwload_status)) {
 				tas_priv->tasdevice[i].cur_conf = -1;
 				tas_priv->tasdevice[i].is_loading = true;
 				prog_status++;
@@ -2228,7 +2228,8 @@ int tasdevice_select_tuningprm_cfg(void *context, int prm_no,
 	}
 
 	for (i = 0, status = 0; i < tas_priv->ndev; i++) {
-		if (tas_priv->tasdevice[i].cur_conf != cfg_no
+		if (cfg_no >= 0
+			&& tas_priv->tasdevice[i].cur_conf != cfg_no
 			&& (cfg_info[rca_conf_no]->active_dev & (1 << i))
 			&& (tas_priv->tasdevice[i].is_loaderr == false)) {
 			status++;
@@ -2238,6 +2239,7 @@ int tasdevice_select_tuningprm_cfg(void *context, int prm_no,
 	}
 
 	if (status) {
+		conf = &(tas_fmw->configs[cfg_no]);
 		status = 0;
 		tasdevice_load_data(tas_priv, &(conf->dev_data));
 		for (i = 0; i < tas_priv->ndev; i++) {
@@ -2281,7 +2283,7 @@ int tasdevice_prmg_load(void *context, int prm_no)
 	}
 
 	for (i = 0, prog_status = 0; i < tas_priv->ndev; i++) {
-		if (tas_priv->tasdevice[i].cur_prog != prm_no) {
+		if (prm_no >= 0 && tas_priv->tasdevice[i].cur_prog != prm_no) {
 			tas_priv->tasdevice[i].cur_conf = -1;
 			tas_priv->tasdevice[i].is_loading = true;
 			prog_status++;
@@ -2326,7 +2328,7 @@ int tasdevice_prmg_calibdata_load(void *context, int prm_no)
 	}
 
 	for (i = 0, prog_status = 0; i < tas_priv->ndev; i++) {
-		if (tas_priv->tasdevice[i].cur_prog != prm_no) {
+		if (prm_no >= 0 && tas_priv->tasdevice[i].cur_prog != prm_no) {
 			tas_priv->tasdevice[i].cur_conf = -1;
 			tas_priv->tasdevice[i].is_loading = true;
 			prog_status++;