linux-kernel - [PATCH] ASoC: hdac_hda: Avoid unexpected match when pcm

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Date:   Wed,  2 Mar 2022 17:43:51 +0800
From:   Meng Tang <tangmeng@...ontech.com>
To:     perex@...ex.cz, tiwai@...e.com, lgirdwood@...il.com,
        broonie@...nel.org
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        Meng Tang <tangmeng@...ontech.com>
Subject: [PATCH] ASoC: hdac_hda: Avoid unexpected match when pcm_name is "Analog"

pcm name can be "Analog" and "Alt Analog", cpcm->name can be
"Analog Codec DAI" and "Alt Analog Codec DAI". When pcm_name
is "Analog", "Analog Codec DAI" and "Alt Analog Codec DAI" are
both satisfy the 'if (strstr(cpcm->name, pcm_name))' condition,
which may cause the returned cpcm to be "Alt Analog Codec DAI".

Even if we get the pcm name by id, and "Analog Codec DAI" goes
into the loop before "Alt Analog Codec DAI", but I still think
we'd better have multiple insurances against unexpected return
values. After, we can correctly return the expected result
even if other relevant places are changed.

Signed-off-by: Meng Tang <tangmeng@...ontech.com>
---
 sound/soc/codecs/hdac_hda.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/hdac_hda.c b/sound/soc/codecs/hdac_hda.c
index 667f3df239c7..a9f61c7e44ee 100644
--- a/sound/soc/codecs/hdac_hda.c
+++ b/sound/soc/codecs/hdac_hda.c
@@ -363,8 +363,13 @@ static struct hda_pcm *snd_soc_find_pcm_from_dai(struct hdac_hda_priv *hda_pvt,
 	}

 	list_for_each_entry(cpcm, &hcodec->pcm_list_head, list) {
-		if (strstr(cpcm->name, pcm_name))
+		if (strstr(cpcm->name, pcm_name)) {
+			if (strcmp(pcm_name, "Analog") == 0) {
+				if (strstr(cpcm->name, "Alt Analog"))
+					continue;
+			}
 			return cpcm;
+		}
 	}

 	dev_err(&hcodec->core.dev, "didn't find PCM for DAI %s\n", dai->name);
-- 
2.20.1