On Tue, 27 Nov 2018 18:05:04 +0100
Nicholas Mc Guire <hofrat@xxxxxxxxx> wrote:
> 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@xxxxxxxxx>
> Fixes: 2051f25d2a26 ("iio: adc: New driver for AD7280A Lithium Ion Battery Monitoring System2")
Hmm. If this had been other than to a staging driver I think I would
have asked you to split this into a rework patch doing the local variable
change, then one actually making the fix. Good result though,
so as it's in staging we'll go with this :)
Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.
Thanks,
Jonathan
> ---
>
> V2: use a tmp pointer to iio_attr to make the error check more readable
> as proposed by Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> Problem located with an experimental coccinelle script
>
> Patch was compile tested with: x86_64_defconfig + STAGING=y
> SPI=y, IIO=y, AD7280=m
>
> Patch is against 4.20-rc4 (localversion-next is next-20181127)
>
> drivers/staging/iio/adc/ad7280a.c | 43 +++++++++++++++++++--------------------
> 1 file changed, 21 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
> index 0bb9ab1..7a0ba26 100644
> --- 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;
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