2018-05-22 11:39:38

by Wei Yongjun

Subject: [PATCH -next] slimbus: qcom: fix potential NULL dereference in qcom_slim_prg_slew()

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

Fixes: ad7fcbc308b0 ("slimbus: qcom: Add Qualcomm Slimbus controller driver")
Signed-off-by: Wei Yongjun <[email protected]>
---
drivers/slimbus/qcom-ctrl.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/slimbus/qcom-ctrl.c b/drivers/slimbus/qcom-ctrl.c
index bb36a8f..caea3b9 100644
--- a/drivers/slimbus/qcom-ctrl.c
+++ b/drivers/slimbus/qcom-ctrl.c
@@ -478,6 +478,8 @@ static void qcom_slim_prg_slew(struct platform_device *pdev,
/* SLEW RATE register for this SLIMbus */
slew_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM,
"slew");
+ if (!slew_mem)
+ return;
ctrl->slew_reg = devm_ioremap(&pdev->dev, slew_mem->start,
resource_size(slew_mem));
if (!ctrl->slew_reg)

2018-05-23 13:43:00

by Srinivas Kandagatla

Subject: Re: [PATCH -next] slimbus: qcom: fix potential NULL dereference in qcom_slim_prg_slew()

On 22/05/18 12:46, Wei Yongjun wrote:
> 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_byname(pdev, t, n);
> + if (!res)
> + return -EINVAL;
> ... when != res == NULL
> e = devm_ioremap(e1, res->start, e2);
>

> Fixes: ad7fcbc308b0 ("slimbus: qcom: Add Qualcomm Slimbus controller driver")
> Signed-off-by: Wei Yongjun <[email protected]>
> ---
> drivers/slimbus/qcom-ctrl.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/slimbus/qcom-ctrl.c b/drivers/slimbus/qcom-ctrl.c
> index bb36a8f..caea3b9 100644
> --- a/drivers/slimbus/qcom-ctrl.c
> +++ b/drivers/slimbus/qcom-ctrl.c
> @@ -478,6 +478,8 @@ static void qcom_slim_prg_slew(struct platform_device *pdev,
> /* SLEW RATE register for this SLIMbus */
> slew_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> "slew");
> + if (!slew_mem)
> + return;

I think a better fix would be to do a devm_ioremap_resource() instead of
devm_ioremap, which already has this check. This will also be inline
with other resource handled in this driver.

thanks,
srini
> ctrl->slew_reg = devm_ioremap(&pdev->dev, slew_mem->start,
> resource_size(slew_mem));
> if (!ctrl->slew_reg)
>