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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>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 3.18 159/185] ALSA: vmaster: Propagate slave error
Date:   Mon, 28 May 2018 12:03:20 +0200
Message-Id: <20180528100111.271339579@linuxfoundation.org>
In-Reply-To: <20180528100050.700971285@linuxfoundation.org>
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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit 2e2c177ca84aff092c3c96714b0f6a12900f3946 ]

In slave_update() of vmaster code ignores the error from the slave
get() callback and copies the values.  It's not only about the missing
error code but also that this may potentially lead to a leak of
uninitialized variables when the slave get() don't clear them.

This patch fixes slave_update() not to copy the potentially
uninitialized values when an error is returned from the slave get()
callback, and to propagate the error value properly.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/core/vmaster.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -68,10 +68,13 @@ static int slave_update(struct link_slav
 		return -ENOMEM;
 	uctl->id = slave->slave.id;
 	err = slave->slave.get(&slave->slave, uctl);
+	if (err < 0)
+		goto error;
 	for (ch = 0; ch < slave->info.count; ch++)
 		slave->vals[ch] = uctl->value.integer.value[ch];
+ error:
 	kfree(uctl);
-	return 0;
+	return err < 0 ? err : 0;
 }
 
 /* get the slave ctl info and save the initial values */