On 2022-12-19 23:17, Miaoqian Lin wrote:
> When all references are dropped, callback function plx_dma_release()
> for put_device() will call kfree(plxdev) to release memory.
> Fix the error path to fix the possible double free.
>
> Fixes: 07503e6aefe4 ("dmaengine: plx_dma: add a missing put_device() on error path")
> Signed-off-by: Miaoqian Lin <linmq006@xxxxxxxxx>
> ---
> Please correct me if I make mistakes, thanks for your review.
> ---
> drivers/dma/plx_dma.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/plx_dma.c b/drivers/dma/plx_dma.c
> index 12725fa1655f..bce724ff4e16 100644
> --- a/drivers/dma/plx_dma.c
> +++ b/drivers/dma/plx_dma.c
> @@ -546,8 +546,9 @@ static int plx_dma_create(struct pci_dev *pdev)
> return 0;
>
> put_device:
> - put_device(&pdev->dev);
> free_irq(pci_irq_vector(pdev, 0), plxdev);
> + put_device(&pdev->dev);
> + return rc;
> free_plx:
> kfree(plxdev);
>
Sorry, after reviewing, I don't think this patch is correct.
plx_dma_release() is called from dma_async_device_unregister() which
won't be called if dma_async_device_register() fails. It does not get
freed when the pci device is put. So I don't think this is a possible
double free.
Logan
