[PATCH -next] clk: imx: fix potential NULL dereference in imx8qxp_lpcg_clk_probe()

[PATCH -next] clk: imx: fix potential NULL dereference in imx8qxp_lpcg_clk_probe()

[Wei Yongjun]

platform_get_resource() may fail and return NULL, so we should
better check it's return value to avoid a NULL pointer dereference
a bit later in the code.

This is detected by Coccinelle semantic patch.

@@
expression pdev, res, n, t, e, e1, e2;
@@

res = platform_get_resource(pdev, t, n);
+ if (!res)
+   return -EINVAL;
... when != res == NULL
e = devm_ioremap(e1, res->start, e2);

Fixes: 1e3121bfe51a ("clk: imx: add imx8qxp lpcg driver")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
---
 drivers/clk/imx/clk-imx8qxp-lpcg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c b/drivers/clk/imx/clk-imx8qxp-lpcg.c
index dcae1dd..8f241a4 100644
--- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
+++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
@@ -169,6 +169,8 @@ static int imx8qxp_lpcg_clk_probe(struct platform_device *pdev)
 		return -ENODEV;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
 	base = devm_ioremap(dev, res->start, resource_size(res));
 	if (!base)
 		return -ENOMEM;

Re: [PATCH -next] clk: imx: fix potential NULL dereference in imx8qxp_lpcg_clk_probe()

[Fabio Estevam]

Hi Wei,

On Tue, Dec 18, 2018 at 4:36 AM Wei Yongjun <weiyongjun1@huawei.com> wrote:

>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res)
> +               return -EINVAL;
>         base = devm_ioremap(dev, res->start, resource_size(res));

Wouldn't it be better to use devm_ioremap_resource(), which does the NULL check?

RE: [PATCH -next] clk: imx: fix potential NULL dereference in imx8qxp_lpcg_clk_probe()

[Aisheng Dong]

> -----Original Message-----
> From: Fabio Estevam [mailto:festevam@gmail.com]
> Hi Wei,
> 
> On Tue, Dec 18, 2018 at 4:36 AM Wei Yongjun <weiyongjun1@huawei.com>
> wrote:
> 
> >         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       if (!res)
> > +               return -EINVAL;
> >         base = devm_ioremap(dev, res->start, resource_size(res));
> 
> Wouldn't it be better to use devm_ioremap_resource(), which does the NULL
> check?

No, devm_ioremap_resource will call request_mem_region which we don't want
as LPCG memory space may overlap with other modules within the same SS.

This is something like the syscon device does:
drivers/mfd/syscon.c.

Regards
Dong Aisheng

RE: [PATCH -next] clk: imx: fix potential NULL dereference in imx8qxp_lpcg_clk_probe()

[Aisheng Dong]

> -----Original Message-----
> From: Wei Yongjun [mailto:weiyongjun1@huawei.com]
> Sent: Tuesday, December 18, 2018 2:43 PM
[...]
> platform_get_resource() may fail and return NULL, so we should better check
> it's return value to avoid a NULL pointer dereference a bit later in the code.
> 
> This is detected by Coccinelle semantic patch.
> 
> @@
> expression pdev, res, n, t, e, e1, e2;
> @@
> 
> res = platform_get_resource(pdev, t, n);
> + if (!res)
> +   return -EINVAL;
> ... when != res == NULL
> e = devm_ioremap(e1, res->start, e2);
> 
> Fixes: 1e3121bfe51a ("clk: imx: add imx8qxp lpcg driver")
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>

Thanks for reporting this.

Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>

Regards
Dong Aisheng

> ---
>  drivers/clk/imx/clk-imx8qxp-lpcg.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> index dcae1dd..8f241a4 100644
> --- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> +++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> @@ -169,6 +169,8 @@ static int imx8qxp_lpcg_clk_probe(struct
> platform_device *pdev)
>  		return -ENODEV;
> 
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
>  	base = devm_ioremap(dev, res->start, resource_size(res));
>  	if (!base)
>  		return -ENOMEM;
> 
> 

Re: [PATCH -next] clk: imx: fix potential NULL dereference in imx8qxp_lpcg_clk_probe()

[Stephen Boyd]

Quoting Wei Yongjun (2018-12-17 22:43:09)
> platform_get_resource() may fail and return NULL, so we should
> better check it's return value to avoid a NULL pointer dereference
> a bit later in the code.
> 
> This is detected by Coccinelle semantic patch.
> 
> @@
> expression pdev, res, n, t, e, e1, e2;
> @@
> 
> res = platform_get_resource(pdev, t, n);
> + if (!res)
> +   return -EINVAL;
> ... when != res == NULL
> e = devm_ioremap(e1, res->start, e2);
> 
> Fixes: 1e3121bfe51a ("clk: imx: add imx8qxp lpcg driver")
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
> ---

Applied to clk-fixes