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SubjectRe: [PATCH -next] slimbus: qcom: fix potential NULL dereference in qcom_slim_prg_slew()
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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 <weiyongjun1@huawei.com>
> ---
> 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)
>

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