Re: [PATCH 2/2] iommu: fix smmu initialization memory leak problem

[liulongfang <liulongfang@huawei.com>]

On 2022/11/15 2:08, Will Deacon Wrote:
> On Fri, Oct 21, 2022 at 11:51:47AM +0800, Longfang Liu wrote:
>> When iommu_device_register() in arm_smmu_device_probe() fails,
>> in addition to sysfs needs to be deleted, device should also
>> be disabled, and the memory of iopf needs to be released to
>> prevent memory leak of iopf.
>>
>> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
>> ---
>>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> index a1db07bed6a9..c70defb0c866 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> @@ -3816,11 +3816,16 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
>>  	ret = iommu_device_register(&smmu->iommu, &arm_smmu_ops, dev);
>>  	if (ret) {
>>  		dev_err(dev, "Failed to register iommu\n");
>> -		iommu_device_sysfs_remove(&smmu->iommu);
>> -		return ret;
>> +		goto err_sysfs_remove;
>>  	}
>>  
>>  	return 0;
>> +
>> +err_sysfs_remove:
>> +	iommu_device_sysfs_remove(&smmu->iommu);
>> +	arm_smmu_device_disable(smmu);
>> +	iopf_queue_free(smmu->evtq.iopf);
>> +	return ret;
> 
> Doesn't this miss the cases where iommu_device_sysfs_add() or
> arm_smmu_device_reset() fail?
> 
> We'd probably be better off using something like devres_alloc() to track
> the iopf queue here.
> 
This is actually not a problem found by the test, but a problem found
by the code logic analysis. When an error exits, the memory allocated
by the iopf queue is not released during the entire exit process.


In addition, it can also be seen from arm_smmu_device_remove()
that the missing operation when the probe error exits.

Thanks
Longfang.
> Will
> .
>