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authorJonathan Cameron <Jonathan.Cameron@huawei.com>2020-07-22 16:50:45 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-09-17 13:47:51 +0200
commitcd1a2517b35e82578abe58578528ef6f1549665b (patch)
tree1355685067f836edb91a29b64d1de7e0f065ba91
parent176fb9423ab8e91ff4776483b81fcc56567f0347 (diff)
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iio:light:max44000 Fix timestamp alignment and prevent data leak.
commit 523628852a5f5f34a15252b2634d0498d3cfb347 upstream. One of a class of bugs pointed out by Lars in a recent review. iio_push_to_buffers_with_timestamp assumes the buffer used is aligned to the size of the timestamp (8 bytes). This is not guaranteed in this driver which uses a 16 byte array of smaller elements on the stack. As Lars also noted this anti pattern can involve a leak of data to userspace and that indeed can happen here. We close both issues by moving to a suitable structure in the iio_priv(). This data is allocated with kzalloc so no data can leak appart from previous readings. It is necessary to force the alignment of ts to avoid the padding on x86_32 being different from 64 bit platorms (it alows for 4 bytes aligned 8 byte types. Fixes: 06ad7ea10e2b ("max44000: Initial triggered buffer support") Reported-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: <Stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/iio/light/max44000.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c
index d6d8007ba430..8cc619de2c3a 100644
--- a/drivers/iio/light/max44000.c
+++ b/drivers/iio/light/max44000.c
@@ -75,6 +75,11 @@
struct max44000_data {
struct mutex lock;
struct regmap *regmap;
+ /* Ensure naturally aligned timestamp */
+ struct {
+ u16 channels[2];
+ s64 ts __aligned(8);
+ } scan;
};
/* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */
@@ -488,7 +493,6 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p)
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct max44000_data *data = iio_priv(indio_dev);
- u16 buf[8]; /* 2x u16 + padding + 8 bytes timestamp */
int index = 0;
unsigned int regval;
int ret;
@@ -498,17 +502,17 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p)
ret = max44000_read_alsval(data);
if (ret < 0)
goto out_unlock;
- buf[index++] = ret;
+ data->scan.channels[index++] = ret;
}
if (test_bit(MAX44000_SCAN_INDEX_PRX, indio_dev->active_scan_mask)) {
ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, &regval);
if (ret < 0)
goto out_unlock;
- buf[index] = regval;
+ data->scan.channels[index] = regval;
}
mutex_unlock(&data->lock);
- iio_push_to_buffers_with_timestamp(indio_dev, buf,
+ iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
iio_get_time_ns(indio_dev));
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;