Re: [PATCH 1/2] drm/imx: Fix error handling for a kmemdup() call in imx_pd_bind()

From: Navid Emamdoost
Date: Sat Oct 12 2019 - 15:17:14 EST


On Sat, Oct 12, 2019 at 4:07 AM Markus Elfring <Markus.Elfring@xxxxxx> wrote:
>
> From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
> Date: Sat, 12 Oct 2019 10:30:21 +0200
>
> The return value from a call of the function âkmemdupâ was not checked
> in this function implementation. Thus add the corresponding error handling.
>
> Fixes: 19022aaae677dfa171a719e9d1ff04823ce65a65 ("staging: drm/imx: Add parallel display support")
> Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/imx/parallel-display.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
> index 35518e5de356..39c4798f56b6 100644
> --- a/drivers/gpu/drm/imx/parallel-display.c
> +++ b/drivers/gpu/drm/imx/parallel-display.c
> @@ -210,8 +210,13 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
> return -ENOMEM;
>
> edidp = of_get_property(np, "edid", &imxpd->edid_len);
> - if (edidp)
> + if (edidp) {
> imxpd->edid = kmemdup(edidp, imxpd->edid_len, GFP_KERNEL);
> + if (!imxpd->edid) {
> + devm_kfree(dev, imxpd);

You should not try to free imxpd here as it is a resource-managed
allocation via devm_kzalloc(). It means memory allocated with this
function is
automatically freed on driver detach. So, this patch introduces a double-free.

> + return -ENOMEM;
> + }
> + }
>
> ret = of_property_read_string(np, "interface-pix-fmt", &fmt);
> if (!ret) {
> --
> 2.23.0
>


--
Navid.