ASoC: SOF: ipc4-topology: Harden loops for looking up ALH copiers

Other, non DAI copier widgets could have the same stream name (sname) as the ALH copier and in that case the copier->data is NULL, no alh_data is attached, which could lead to NULL pointer dereference.
We could check for this NULL pointer in sof_ipc4_prepare_copier_module() and avoid the crash, but a similar loop in sof_ipc4_widget_setup_comp_dai() will miscalculate the ALH device count, causing broken audio.

The correct fix is to harden the matching logic by making sure that the
1. widget is a DAI widget - so dai = w->private is valid
2. the dai (and thus the copier) is ALH copier

---
 sound/soc/sof/ipc4-topology.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

index b55eb977e443..70b7bfb080f4 100644
@@ -765,10 +765,16 @@ static int sof_ipc4_widget_setup_comp_dai(struct snd_sof_widget *swidget)
 		}
 
 		list_for_each_entry(w, &sdev->widget_list, list) {
-			if (w->widget->sname &&
+			struct snd_sof_dai *alh_dai;
+
+			if (!WIDGET_IS_DAI(w->id) || !w->widget->sname ||
 			    strcmp(w->widget->sname, swidget->widget->sname))
 				continue;
 
+			alh_dai = w->private;
+			if (alh_dai->type != SOF_DAI_INTEL_ALH)
+				continue;
+
 			blob->alh_cfg.device_count++;
 		}
 

@@ -2061,11 +2067,13 @@ sof_ipc4_prepare_copier_module(struct snd_sof_widget *swidget,
 			list_for_each_entry(w, &sdev->widget_list, list) {
 				u32 node_type;
 
-				if (w->widget->sname &&
+				if (!WIDGET_IS_DAI(w->id) || !w->widget->sname ||
 				    strcmp(w->widget->sname, swidget->widget->sname))
 					continue;
 
 				dai = w->private;
+				if (dai->type != SOF_DAI_INTEL_ALH)
+					continue;
 				alh_copier = (struct sof_ipc4_copier *)dai->private;
 				alh_data = &alh_copier->data;
 				node_type = SOF_IPC4_GET_NODE_TYPE(alh_data->gtw_cfg.node_id);

2.47.1

This commit is not in mainline.

Applied to

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: SOF: ipc4-topology: Harden loops for looking up ALH copiers

      commit: 6fd60136d256b3b948333ebdb3835f41a95ab7ef

All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.

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Thanks,
Mark