linux-kernel - [PATCH 3.16 11/72] ALSA: aoa: onyx: always initialize register read value

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Message-ID: <lsq.1575813165.135913355@decadent.org.uk>
Date:   Sun, 08 Dec 2019 13:52:55 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Stephen Rothwell" <sfr@...b.auug.org.au>,
        "Johannes Berg" <johannes@...solutions.net>,
        "Takashi Iwai" <tiwai@...e.de>
Subject: [PATCH 3.16 11/72] ALSA: aoa: onyx: always initialize register
 read value

3.16.79-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Johannes Berg <johannes@...solutions.net>

commit f474808acb3c4b30552d9c59b181244e0300d218 upstream.

A lot of places in the driver use onyx_read_register() without
checking the return value, and it's been working OK for ~10 years
or so, so probably never fails ... Rather than trying to check the
return value everywhere, which would be relatively intrusive, at
least make sure we don't use an uninitialized value.

Fixes: f3d9478b2ce4 ("[ALSA] snd-aoa: add snd-aoa")
Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
Signed-off-by: Johannes Berg <johannes@...solutions.net>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 sound/aoa/codecs/onyx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/sound/aoa/codecs/onyx.c
+++ b/sound/aoa/codecs/onyx.c
@@ -74,8 +74,10 @@ static int onyx_read_register(struct ony
 		return 0;
 	}
 	v = i2c_smbus_read_byte_data(onyx->i2c, reg);
-	if (v < 0)
+	if (v < 0) {
+		*value = 0;
 		return -1;
+	}
 	*value = (u8)v;
 	onyx->cache[ONYX_REG_CONTROL-FIRSTREGISTER] = *value;
 	return 0;