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SubjectRe: [PATCH] mmc: cqhci: Fix a tiny potential memory leak on error condition
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On 31/01/19 12:10 PM, Adrian Hunter wrote:
> On 16/01/19 2:24 AM, Alamy Liu wrote:
>> In the error case:
>> either cq_host->desc_base
>> or cq_host->trans_desc_base
>> might have been granted memory successfully.
>>
>> The value of mmc_host->cqe_enabled stays 'false'.
>> Thus, cqhci_disable (mmc_cqe_ops->cqe_disable) won't be called to
>> free the memory.
>> Also, cqhci_disable() is designed to disable and free all resources,
>> not suitable to handle this corner case.
>>
>> Signed-off-by: Alamy Liu <alamy.liu@gmail.com>
>> ---
>> drivers/mmc/host/cqhci.c | 20 +++++++++++++++++++-
>> 1 file changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/cqhci.c b/drivers/mmc/host/cqhci.c
>> index 974997b6cb..58ad8cd613 100644
>> --- a/drivers/mmc/host/cqhci.c
>> +++ b/drivers/mmc/host/cqhci.c
>> @@ -223,7 +223,7 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
>> &cq_host->trans_desc_dma_base,
>> GFP_KERNEL);
>> if (!cq_host->desc_base || !cq_host->trans_desc_base)
>> - return -ENOMEM;
>> + goto err_free_dma;
>>
>> pr_debug("%s: cqhci: desc-base: 0x%p trans-base: 0x%p\n desc_dma 0x%llx trans_dma: 0x%llx\n",
>> mmc_hostname(cq_host->mmc), cq_host->desc_base, cq_host->trans_desc_base,
>> @@ -234,6 +234,24 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
>> setup_trans_desc(cq_host, i);
>>
>> return 0;
>> +
>> +err_free_dma:
>> + if (cq_host->desc_base) {
>> + dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->desc_size,
>> + cq_host->desc_base,
>> + cq_host->desc_dma_base);
>> + cq_host->desc_base = NULL;
>> + cq_host->desc_dma_base = 0;
>> + }
>> + if (cq_host->trans_desc_base) {
>> + dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->data_size,
>> + cq_host->trans_desc_base,
>> + cq_host->trans_desc_dma_base);
>> + cq_host->trans_desc_base = NULL;
>> + cq_host->trans_desc_dma_base = 0;
>> + }
>> +
>> + return -ENOMEM;
>> }
>>
>> static void __cqhci_enable(struct cqhci_host *cq_host)
>>
>
> Normally, error handling is done step-by-step e.g.
>
> diff --git a/drivers/mmc/host/cqhci.c b/drivers/mmc/host/cqhci.c
> index 26d63594b7ea..d015b465ade4 100644
> --- a/drivers/mmc/host/cqhci.c
> +++ b/drivers/mmc/host/cqhci.c
> @@ -217,12 +217,15 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
> cq_host->desc_size,
> &cq_host->desc_dma_base,
> GFP_KERNEL);
> + if (!cq_host->desc_base)
> + return -ENOMEM;
> +
> cq_host->trans_desc_base = dmam_alloc_coherent(mmc_dev(cq_host->mmc),
> cq_host->data_size,
> &cq_host->trans_desc_dma_base,
> GFP_KERNEL);
> - if (!cq_host->desc_base || !cq_host->trans_desc_base)
> - return -ENOMEM;
> + if (!cq_host->trans_desc_base)
> + goto err_free_dma;
>
> pr_debug("%s: cqhci: desc-base: 0x%p trans-base: 0x%p\n desc_dma 0x%llx trans_dma: 0x%llx\n",
> mmc_hostname(cq_host->mmc), cq_host->desc_base, cq_host->trans_desc_base,
> @@ -233,6 +236,13 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
> setup_trans_desc(cq_host, i);
>
> return 0;
> +
> +err_free_dma:
> + dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->desc_size,
> + cq_host->desc_base, cq_host->desc_dma_base);
> + cq_host->desc_base = NULL;
> + cq_host->desc_dma_base = 0;
> + return NULL;

That should be
return -ENOMEM;

> }
>
> static void __cqhci_enable(struct cqhci_host *cq_host)
>

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