2022-06-24 01:51:52

by Jiapeng Chong

Subject: [PATCH] drm/ingenic: Use resource_size function on resource object

This was found by coccicheck:

./drivers/gpu/drm/ingenic/ingenic-drm-drv.c:1149:35-38: WARNING: Suspicious code. resource_size is maybe missing with res.

Signed-off-by: Jiapeng Chong <[email protected]>
---
drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
index 2c559885347a..5514b163999f 100644
--- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
@@ -1146,7 +1146,7 @@ static int ingenic_drm_bind(struct device *dev, bool has_components)
}

regmap_config = ingenic_drm_regmap_config;
- regmap_config.max_register = res->end - res->start;
+ regmap_config.max_register = resource_size(res);
priv->map = devm_regmap_init_mmio(dev, base,
&regmap_config);
if (IS_ERR(priv->map)) {
--
2.20.1.7.g153144c

2022-06-24 17:32:53

by Sam Ravnborg

Subject: Re: [PATCH] drm/ingenic: Use resource_size function on resource object

Hi Jiapeng,

On Fri, Jun 24, 2022 at 09:31:59AM +0800, Jiapeng Chong wrote:
> This was found by coccicheck:
>
> ./drivers/gpu/drm/ingenic/ingenic-drm-drv.c:1149:35-38: WARNING: Suspicious code. resource_size is maybe missing with res.
>
Nice one, now I have to go back and fix my code as well.

> Signed-off-by: Jiapeng Chong <[email protected]>
Reviewed-by: Sam Ravnborg <[email protected]>

2022-06-24 19:10:14

by Paul Cercueil

Subject: Re: [PATCH] drm/ingenic: Use resource_size function on resource object

Hi,

Le ven., juin 24 2022 at 09:31:59 +0800, Jiapeng Chong
<[email protected]> a ?crit :
> This was found by coccicheck:
>
> ./drivers/gpu/drm/ingenic/ingenic-drm-drv.c:1149:35-38: WARNING:
> Suspicious code. resource_size is maybe missing with res.
>
> Signed-off-by: Jiapeng Chong <[email protected]>
> ---
> drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index 2c559885347a..5514b163999f 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -1146,7 +1146,7 @@ static int ingenic_drm_bind(struct device *dev,
> bool has_components)
> }
>
> regmap_config = ingenic_drm_regmap_config;
> - regmap_config.max_register = res->end - res->start;
> + regmap_config.max_register = resource_size(res);

These two are not equivalent. resource_size() is (res->end - res->start
+ 1).

If the memory resource has a size of 0x10 bytes, then using
resource_size() will set .max_register == 0x10, which is invalid, as it
is already outside the memory resource.

Cheers,
-Paul


> priv->map = devm_regmap_init_mmio(dev, base,
> &regmap_config);
> if (IS_ERR(priv->map)) {
> --
> 2.20.1.7.g153144c
>