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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Takashi Iwai <tiwai@suse.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH 4.4 134/135] ALSA: usb-audio: Fix invalid NULL check in snd_emuusb_set_samplerate()
Date:   Mon, 29 Jun 2020 11:53:08 -0400
Message-Id: <20200629155309.2495516-135-sashal@kernel.org>
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From: Takashi Iwai <tiwai@suse.de>

commit 6de3c9e3f6b3eaf66859e1379b3f35dda781416b upstream.

The quirk function snd_emuusb_set_samplerate() has a NULL check for
the mixer element, but this is useless in the current code.  It used
to be a check against mixer->id_elems[unitid] but it was changed later
to the value after mixer_eleme_list_to_info() which is always non-NULL
due to the container_of() usage.

This patch fixes the check before the conversion.

While we're at it, correct a typo in the comment in the function,
too.

Fixes: 8c558076c740 ("ALSA: usb-audio: Clean up mixer element list traverse")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/usb/mixer_quirks.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 198515f86fcc2..9646513f4b4ad 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1168,17 +1168,17 @@ void snd_emuusb_set_samplerate(struct snd_usb_audio *chip,
 {
 	struct usb_mixer_interface *mixer;
 	struct usb_mixer_elem_info *cval;
-	int unitid = 12; /* SamleRate ExtensionUnit ID */
+	int unitid = 12; /* SampleRate ExtensionUnit ID */
 
 	list_for_each_entry(mixer, &chip->mixer_list, list) {
-		cval = mixer_elem_list_to_info(mixer->id_elems[unitid]);
-		if (cval) {
+		if (mixer->id_elems[unitid]) {
+			cval = mixer_elem_list_to_info(mixer->id_elems[unitid]);
 			snd_usb_mixer_set_ctl_value(cval, UAC_SET_CUR,
 						    cval->control << 8,
 						    samplerate_id);
 			snd_usb_mixer_notify_id(mixer, unitid);
+			break;
 		}
-		break;
 	}
 }
 
-- 
2.25.1