[PATCH] ALSA: ASoC: fix ak4104 register array access

[PATCH] ALSA: ASoC: fix ak4104 register array access

[Daniel Mack]

Don't touch the variable 'reg' to construct the value for the actual SPI
transport. This variable is again used to access the driver's register
cache, and so random memory is overwritten.
Compute the value in-place instead.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@kernel.org
---
 sound/soc/codecs/ak4104.c |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/sound/soc/codecs/ak4104.c b/sound/soc/codecs/ak4104.c
index b9ef7e4..b68d99f 100644
--- a/sound/soc/codecs/ak4104.c
+++ b/sound/soc/codecs/ak4104.c
@@ -90,12 +90,10 @@ static int ak4104_spi_write(struct snd_soc_codec *codec, unsigned int reg,
 	if (reg >= codec->reg_cache_size)
 		return -EINVAL;
 
-	reg &= AK4104_REG_MASK;
-	reg |= AK4104_WRITE;
-
 	/* only write to the hardware if value has changed */
 	if (cache[reg] != value) {
-		u8 tmp[2] = { reg, value };
+		u8 tmp[2] = { (reg & AK4104_REG_MASK) | AK4104_WRITE, value };
+
 		if (spi_write(spi, tmp, sizeof(tmp))) {
 			dev_err(&spi->dev, "SPI write failed\n");
 			return -EIO;
-- 
1.6.3.3

Re: [PATCH] ALSA: ASoC: fix ak4104 register array access

[Mark Brown]

On Fri, Feb 26, 2010 at 02:36:54PM +0800, Daniel Mack wrote:
> Don't touch the variable 'reg' to construct the value for the actual SPI
> transport. This variable is again used to access the driver's register
> cache, and so random memory is overwritten.
> Compute the value in-place instead.
> 
> Signed-off-by: Daniel Mack <daniel@caiaq.de>
> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
> Cc: stable@kernel.org

Applied, thanks.  Please CC Liam on ASoC commits.