Re: [PATCH v2] iommu/qcom: Fix local_base status check

Re: [PATCH v2] iommu/qcom: Fix local_base status check

[Markus Elfring]

> The function qcom_iommu_device_probe() does not perform sufficient
> error checking after executing devm_ioremap_resource(), which can
> result in crashes if a critical error path is encountered.

Your update suggestion will be rechecked once more.

* Can it be that the patch would need a higher version number
  according to previous review comments?

* Would you like to adjust the patch subject?


…
> +++ b/drivers/iommu/qcom_iommu.c
> @@ -813,8 +813,11 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
>  	qcom_iommu->dev = dev;
>
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (res)

I find the deletion of this check appropriate.


> +	if (res) {
>  		qcom_iommu->local_base = devm_ioremap_resource(dev, res);

But I do not see a need to preserve such a check because this function
performs input parameter validation.
https://elixir.bootlin.com/linux/v5.7-rc1/source/lib/devres.c#L116
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/devres.c?id=50cc09c18985eacbbd666acfd7be2391394733f5#n116

Please take another look at a corresponding usage example.

Regards,
Markus
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Re: [PATCH v2] iommu/qcom: Fix local_base status check

[Markus Elfring]

> …
>> +++ b/drivers/iommu/qcom_iommu.c
>> @@ -813,8 +813,11 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
>>  	qcom_iommu->dev = dev;
>>
>>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
…
>>  		qcom_iommu->local_base = devm_ioremap_resource(dev, res);
…
> Please take another look at a corresponding usage example.

I would like to point another possibility out for desirable software evolution.
How do you think about to call a “known” wrapper function instead?

devm_platform_get_and_ioremap_resource
https://elixir.bootlin.com/linux/v5.7-rc1/source/drivers/base/platform.c#L66
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/drivers/base/platform.c

Regards,
Markus
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[PATCH v2]iommu/qcom:fix local_base status check

[Tang Bin]

The function qcom_iommu_device_probe() does not perform sufficient
error checking after executing devm_ioremap_resource(), which can
result in crashes if a critical error path is encountered.

Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu")

Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
---
v2:
 - fix commit message and add fixed tag
---
 drivers/iommu/qcom_iommu.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c
index 4328da0b0..b160cf140 100644
--- a/drivers/iommu/qcom_iommu.c
+++ b/drivers/iommu/qcom_iommu.c
@@ -813,8 +813,11 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
 	qcom_iommu->dev = dev;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (res)
+	if (res) {
 		qcom_iommu->local_base = devm_ioremap_resource(dev, res);
+		if (IS_ERR(qcom_iommu->local_base))
+			return PTR_ERR(qcom_iommu->local_base);
+	}
 
 	qcom_iommu->iface_clk = devm_clk_get(dev, "iface");
 	if (IS_ERR(qcom_iommu->iface_clk)) {
-- 
2.20.1.windows.1



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Re: [PATCH v2]iommu/qcom:fix local_base status check

[Bjorn Andersson]

On Sat 18 Apr 06:47 PDT 2020, Tang Bin wrote:

> The function qcom_iommu_device_probe() does not perform sufficient
> error checking after executing devm_ioremap_resource(), which can
> result in crashes if a critical error path is encountered.
> 

Thanks, that's much better.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu")
> 
> Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
> ---
> v2:
>  - fix commit message and add fixed tag
> ---
>  drivers/iommu/qcom_iommu.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c
> index 4328da0b0..b160cf140 100644
> --- a/drivers/iommu/qcom_iommu.c
> +++ b/drivers/iommu/qcom_iommu.c
> @@ -813,8 +813,11 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
>  	qcom_iommu->dev = dev;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (res)
> +	if (res) {
>  		qcom_iommu->local_base = devm_ioremap_resource(dev, res);
> +		if (IS_ERR(qcom_iommu->local_base))
> +			return PTR_ERR(qcom_iommu->local_base);
> +	}
>  
>  	qcom_iommu->iface_clk = devm_clk_get(dev, "iface");
>  	if (IS_ERR(qcom_iommu->iface_clk)) {
> -- 
> 2.20.1.windows.1
> 
> 
> 
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Re: [PATCH v2]iommu/qcom:fix local_base status check

[Joerg Roedel]

On Sat, Apr 18, 2020 at 09:47:03PM +0800, Tang Bin wrote:
> The function qcom_iommu_device_probe() does not perform sufficient
> error checking after executing devm_ioremap_resource(), which can
> result in crashes if a critical error path is encountered.
> 
> Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu")
> 
> Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
> ---
> v2:
>  - fix commit message and add fixed tag
> ---
>  drivers/iommu/qcom_iommu.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Applied for v5.7, thanks.

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Re: [PATCH v2]iommu/qcom:fix local_base status check

[Tang Bin]

On 2020/5/1 19:37, Joerg Roedel wrote:
> On Sat, Apr 18, 2020 at 09:47:03PM +0800, Tang Bin wrote:
>> The function qcom_iommu_device_probe() does not perform sufficient
>> error checking after executing devm_ioremap_resource(), which can
>> result in crashes if a critical error path is encountered.
>>
>> Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu")
>>
>> Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
>> ---
>> v2:
>>   - fix commit message and add fixed tag
>> ---
>>   drivers/iommu/qcom_iommu.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
> Applied for v5.7, thanks.

Thank you very much.

Tang Bin

>


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Re: [PATCH v2] iommu/qcom: Fix local_base status check

[Markus Elfring]

> Release resources when exiting on error.

I have got doubts that such a change description fits to
the proposed source code adjustment.


…
> +++ b/drivers/iommu/qcom_iommu.c
> @@ -813,8 +813,11 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
>  	qcom_iommu->dev = dev;
>
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (res)
> +	if (res) {
>  		qcom_iommu->local_base = devm_ioremap_resource(dev, res);
> +		if (IS_ERR(qcom_iommu->local_base))
> +			return PTR_ERR(qcom_iommu->local_base);
> +	}
>
>  	qcom_iommu->iface_clk = devm_clk_get(dev, "iface");
…

Will the commit message be improved any further?

Would you like to add the tag “Fixes”?

Regards,
Markus
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