staging: iio: adc: ad7280a: check for devm_kasprint() failure

devm_kasprintf() may return NULL on failure of internal allocation thus
the assignments to  attr.name  are not safe if not checked. On error
ad7280_attr_init() returns a negative return so -ENOMEM should be
OK here (passed on as return value of the probe function). To make the
error case more readable a temporary  iio_attr  is introduced and the code
refactored.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: 2051f25d2a26 ("iio: adc: New driver for AD7280A Lithium Ion Battery Monitoring System2")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
index 0bb9ab174f2ac0a0824b5a5d4543f5bf8c3df5ce..7a0ba26f9fd9fc4e844cffc271f04e2f98880c10 100644 (file)
--- a/drivers/staging/iio/adc/ad7280a.c
+++ b/drivers/staging/iio/adc/ad7280a.c
@@ -561,6 +561,7 @@ static int ad7280_attr_init(struct ad7280_state *st)
 {
        int dev, ch, cnt;
        unsigned int index;
+       struct iio_dev_attr *iio_attr;
 
        st->iio_attr = devm_kcalloc(&st->spi->dev, 2, sizeof(*st->iio_attr) *
                                    (st->slave_num + 1) * AD7280A_CELLS_PER_DEV,
@@ -571,37 +572,35 @@ static int ad7280_attr_init(struct ad7280_state *st)
        for (dev = 0, cnt = 0; dev <= st->slave_num; dev++)
                for (ch = AD7280A_CELL_VOLTAGE_1; ch <= AD7280A_CELL_VOLTAGE_6;
                        ch++, cnt++) {
+                       iio_attr = &st->iio_attr[cnt];
                        index = dev * AD7280A_CELLS_PER_DEV + ch;
-                       st->iio_attr[cnt].address =
-                               ad7280a_devaddr(dev) << 8 | ch;
-                       st->iio_attr[cnt].dev_attr.attr.mode =
-                               0644;
-                       st->iio_attr[cnt].dev_attr.show =
-                               ad7280_show_balance_sw;
-                       st->iio_attr[cnt].dev_attr.store =
-                               ad7280_store_balance_sw;
-                       st->iio_attr[cnt].dev_attr.attr.name =
+                       iio_attr->address = ad7280a_devaddr(dev) << 8 | ch;
+                       iio_attr->dev_attr.attr.mode = 0644;
+                       iio_attr->dev_attr.show = ad7280_show_balance_sw;
+                       iio_attr->dev_attr.store = ad7280_store_balance_sw;
+                       iio_attr->dev_attr.attr.name =
                                devm_kasprintf(&st->spi->dev, GFP_KERNEL,
                                               "in%d-in%d_balance_switch_en",
                                               index, index + 1);
-                       ad7280_attributes[cnt] =
-                               &st->iio_attr[cnt].dev_attr.attr;
+                       if (!iio_attr->dev_attr.attr.name)
+                               return -ENOMEM;
+
+                       ad7280_attributes[cnt] = &iio_attr->dev_attr.attr;
                        cnt++;
-                       st->iio_attr[cnt].address =
-                               ad7280a_devaddr(dev) << 8 |
+                       iio_attr = &st->iio_attr[cnt];
+                       iio_attr->address = ad7280a_devaddr(dev) << 8 |
                                (AD7280A_CB1_TIMER + ch);
-                       st->iio_attr[cnt].dev_attr.attr.mode =
-                               0644;
-                       st->iio_attr[cnt].dev_attr.show =
-                               ad7280_show_balance_timer;
-                       st->iio_attr[cnt].dev_attr.store =
-                               ad7280_store_balance_timer;
-                       st->iio_attr[cnt].dev_attr.attr.name =
+                       iio_attr->dev_attr.attr.mode = 0644;
+                       iio_attr->dev_attr.show = ad7280_show_balance_timer;
+                       iio_attr->dev_attr.store = ad7280_store_balance_timer;
+                       iio_attr->dev_attr.attr.name =
                                devm_kasprintf(&st->spi->dev, GFP_KERNEL,
                                               "in%d-in%d_balance_timer",
                                               index, index + 1);
-                       ad7280_attributes[cnt] =
-                               &st->iio_attr[cnt].dev_attr.attr;
+                       if (!iio_attr->dev_attr.attr.name)
+                               return -ENOMEM;
+
+                       ad7280_attributes[cnt] = &iio_attr->dev_attr.attr;
                }
 
        ad7280_attributes[cnt] = NULL;