linux-kernel - Re: [PATCH v2] PCI: endpoint: functions/pci-epf-test: Avoid DMA release when DMA is unsupported

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Message-ID: <95116fe1-7908-1948-9f1e-bf4c8b5f2e2d@ti.com>
Date:   Wed, 22 Apr 2020 13:26:34 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] PCI: endpoint: functions/pci-epf-test: Avoid DMA
 release when DMA is unsupported

Hi Kunihiko,

On 4/22/2020 12:54 PM, Kunihiko Hayashi wrote:
> When unbinding pci_epf_test, pci_epf_test_clean_dma_chan() is called in
> pci_epf_test_unbind() even though epf_test->dma_supported is false.
> As a result, dma_release_channel() will occur null pointer access because
> dma_chan isn't set.
> 
> This avoids calling dma_release_channel() if epf_test->dma_supported
> is false.
> 
> Fixes: a1d105d4ab8e ("PCI: endpoint: functions/pci-epf-test: Add DMA support to transfer data")
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>

Thank you for fixing this.

Acked-by: Kishon Vijay Abraham I <kishon@...com>

Regards
Kishon

> ---
>  drivers/pci/endpoint/functions/pci-epf-test.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 60330f3e..c89a956 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -187,6 +187,9 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
>   */
>  static void pci_epf_test_clean_dma_chan(struct pci_epf_test *epf_test)
>  {
> +	if (!epf_test->dma_supported)
> +		return;
> +
>  	dma_release_channel(epf_test->dma_chan);
>  	epf_test->dma_chan = NULL;
>  }
>