linux-kernel - [PATCH 4.11 67/78] iio: adc: meson-saradc: fix potential crash in meson_sar_adc_clear

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Message-Id: <20170619151031.935394642@linuxfoundation.org>
Date:   Mon, 19 Jun 2017 23:16:07 +0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Paolo Cretaro <paolocretaro@...il.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Jonathan Cameron <jic23@...nel.org>
Subject: [PATCH 4.11 67/78] iio: adc: meson-saradc: fix potential crash in meson_sar_adc_clear_fifo

4.11-stable review patch.  If anyone has any objections, please let me know.

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

From: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

commit 103a07d4278203d6299798cd74cdc4d209801cac upstream.

meson_sar_adc_clear_fifo passes a 0 as value-pointer to regmap_read().
In case of the meson-saradc driver this ends up in regmap_mmio_read(),
where the value-pointer is de-referenced unconditionally to assign the
value which was read.
Fix this by passing an actual pointer, even though all we want to do is
to discard the value.

As a side-effect this fixes a sparse warning ("Using plain integer as
NULL pointer") as reported by Paolo Cretaro.

Fixes: 3adbf3427330 ("iio: adc: add a driver for the SAR ADC found in Amlogic Meson SoCs")
Reported-by: Paolo Cretaro <paolocretaro@...il.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Signed-off-by: Jonathan Cameron <jic23@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iio/adc/meson_saradc.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/iio/adc/meson_saradc.c
+++ b/drivers/iio/adc/meson_saradc.c
@@ -440,13 +440,13 @@ static void meson_sar_adc_unlock(struct
 static void meson_sar_adc_clear_fifo(struct iio_dev *indio_dev)
 {
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
-	int count;
+	unsigned int count, tmp;
 
 	for (count = 0; count < MESON_SAR_ADC_MAX_FIFO_SIZE; count++) {
 		if (!meson_sar_adc_get_fifo_count(indio_dev))
 			break;
 
-		regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, 0);
+		regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &tmp);
 	}
 }