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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 5.2 065/143] ALSA: usb-audio: Fix invalid NULL check in snd_emuusb_set_samplerate()
Date:   Wed,  4 Sep 2019 19:53:28 +0200
Message-Id: <20190904175316.613456974@linuxfoundation.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(-)

--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1155,17 +1155,17 @@ void snd_emuusb_set_samplerate(struct sn
 {
 	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;
 	}
 }