Re: [PATCH] mmc: cqhci: Fix a tiny potential memory leak on error condition

[Adrian Hunter]

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....@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)