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References: <20240228204919.3680786-1-andriy.shevchenko@linux.intel.com> <20240228204919.3680786-4-andriy.shevchenko@linux.intel.com>
In-Reply-To: <20240228204919.3680786-4-andriy.shevchenko@linux.intel.com>
From: David Lechner <dlechner@baylibre.com>
Date: Wed, 28 Feb 2024 15:06:42 -0600
Message-ID: <CAMknhBFbQ2BmGd18wC0odO-b_bWvJEO3FCYEtpvhB1fF+MEFgg@mail.gmail.com>
Subject: Re: [PATCH v4 3/8] iio: core: NULLify private pointer when there is
 no private data
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Vinod Koul <vkoul@kernel.org>, Linus Walleij <linus.walleij@linaro.org>, 
	Jonathan Cameron <Jonathan.Cameron@huawei.com>, Mark Brown <broonie@kernel.org>, 
	Kees Cook <keescook@chromium.org>, linux-arm-kernel@lists.infradead.org, 
	dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-iio@vger.kernel.org, linux-spi@vger.kernel.org, netdev@vger.kernel.org, 
	linux-hardening@vger.kernel.org, Jonathan Cameron <jic23@kernel.org>, 
	Lars-Peter Clausen <lars@metafoo.de>, "David S. Miller" <davem@davemloft.net>, 
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>, 
	"Gustavo A. R. Silva" <gustavoars@kernel.org>
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On Wed, Feb 28, 2024 at 2:50=E2=80=AFPM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> In iio_device_alloc() when size of the private data is 0,
> the private pointer is calculated to behind the valid data.
> NULLify it for good.
>
> Fixes: 6d4ebd565d15 ("iio: core: wrap IIO device into an iio_dev_opaque o=
bject")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/iio/industrialio-core.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-c=
ore.c
> index 4302093b92c7..bd305fa87093 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1654,8 +1654,12 @@ struct iio_dev *iio_device_alloc(struct device *pa=
rent, int sizeof_priv)
>                 return NULL;
>
>         indio_dev =3D &iio_dev_opaque->indio_dev;
> -       indio_dev->priv =3D (char *)iio_dev_opaque +
> -               ALIGN(sizeof(struct iio_dev_opaque), IIO_DMA_MINALIGN);
> +
> +       if (sizeof_priv)
> +               indio_dev->priv =3D (char *)iio_dev_opaque +
> +                       ALIGN(sizeof(struct iio_dev_opaque), IIO_DMA_MINA=
LIGN);
> +       else
> +               indio_dev->priv =3D NULL;

Do we actually need the else branch here since we use kzalloc() and
therefore indio_dev->priv should already be NULL?

>
>         indio_dev->dev.parent =3D parent;
>         indio_dev->dev.type =3D &iio_device_type;
> --
> 2.43.0.rc1.1.gbec44491f096
>
>