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SubjectRe: [PATCH] mmc: cqhci: Fix a tiny potential memory leak on error condition
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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;
}

static void __cqhci_enable(struct cqhci_host *cq_host)
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