ASoC: qcom: common: Fix refcounting in qcom_snd_parse_of()

There are two issues in this function.

1) We can't drop the refrences on "cpu", "codec" and "platform" before we take the reference. This doesn't cause a problem on the first iteration because those pointers start as NULL so the of_node_put() is a no-op. But on the subsequent iterations, it will lead to a use after free.

2) If the devm_kzalloc() allocation failed then the code returned directly instead of cleaning up.

---
 sound/soc/qcom/common.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

index 54660f126d09..09af00700700 100644
@@ -58,7 +58,7 @@ int qcom_snd_parse_of(struct snd_soc_card *card)
 		dlc = devm_kzalloc(dev, 2 * sizeof(*dlc), GFP_KERNEL);
 		if (!dlc) {
 			ret = -ENOMEM;
-			goto err;
+			goto err_put_np;
 		}
 
 		link->cpus	= &dlc[0];

@@ -70,7 +70,7 @@ int qcom_snd_parse_of(struct snd_soc_card *card)
 		ret = of_property_read_string(np, "link-name", &link->name);
 		if (ret) {
 			dev_err(card->dev, "error getting codec dai_link name\n");
-			goto err;
+			goto err_put_np;
 		}
 
 		cpu = of_get_child_by_name(np, "cpu");

@@ -130,8 +130,10 @@ int qcom_snd_parse_of(struct snd_soc_card *card)
 		} else {
 			/* DPCM frontend */
 			dlc = devm_kzalloc(dev, sizeof(*dlc), GFP_KERNEL);
-			if (!dlc)
-				return -ENOMEM;
+			if (!dlc) {
+				ret = -ENOMEM;
+				goto err;
+			}
 
 			link->codecs	 = dlc;
 			link->num_codecs = 1;

@@ -158,10 +160,11 @@ int qcom_snd_parse_of(struct snd_soc_card *card)
 
 	return 0;
 err:
-	of_node_put(np);
 	of_node_put(cpu);
 	of_node_put(codec);
 	of_node_put(platform);
+err_put_np:
+	of_node_put(np);
 	return ret;
 }
 EXPORT_SYMBOL(qcom_snd_parse_of);

2.28.0

Applied to

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

Thanks!

[1/1] ASoC: qcom: common: Fix refcounting in qcom_snd_parse_of()

      commit: 4e59dd249cd513a211e2ecce2cb31f4e29a5ce5b

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.

You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed.

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Thanks,
Mark