Re: [PATCH 2/6] dmaengine: plx_dma: fix descriptor ring leak in alloc_chan_resources()

[Frank Li]

On Tue, Nov 03, 2026 at 09:51:57AM -0600, Logan Gunthorpe wrote:
> If the device is removed between plx_dma_alloc_desc() and the pdev
> check, the error path frees hw_ring but leaks desc_ring and every
> descriptor in it.
>
> Add plx_dma_free_desc() and use it here and in
> plx_dma_free_chan_resources().
>
> Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
> Link: https://lore.kernel.org/dmaengine/20260717223217.B6FBF1F000E9@xxxxxxxxxxxxxxx
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> ---
>  drivers/dma/plx_dma.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>
> diff --git a/drivers/dma/plx_dma.c b/drivers/dma/plx_dma.c
> index 0a7ad2473cb1..bfccbb0c70e8 100644
> --- a/drivers/dma/plx_dma.c
> +++ b/drivers/dma/plx_dma.c
> @@ -404,6 +404,16 @@ static int plx_dma_alloc_desc(struct plx_dma_dev *plxdev)
>  	return -ENOMEM;
>  }
>
> +static void plx_dma_free_desc(struct plx_dma_dev *plxdev)
> +{
> +	int i;
> +
> +	for (i = 0; i < PLX_DMA_RING_COUNT; i++)
> +		kfree(plxdev->desc_ring[i]);
> +
> +	kfree(plxdev->desc_ring);
> +}
> +
>  static int plx_dma_alloc_chan_resources(struct dma_chan *chan)
>  {
>  	struct plx_dma_dev *plxdev = chan_to_plx_dma_dev(chan);
> @@ -424,7 +434,7 @@ static int plx_dma_alloc_chan_resources(struct dma_chan *chan)
>  	if (!rcu_dereference(plxdev->pdev)) {
>  		rcu_read_unlock();
>  		rc = -ENODEV;
> -		goto out_free_hw_ring;
> +		goto out_free_desc;
>  	}
>
>  	writel(PLX_REG_CTRL_RESET_VAL, plxdev->bar + PLX_REG_CTRL);
> @@ -443,6 +453,8 @@ static int plx_dma_alloc_chan_resources(struct dma_chan *chan)
>
>  	return PLX_DMA_RING_COUNT;
>
> +out_free_desc:
> +	plx_dma_free_desc(plxdev);
>  out_free_hw_ring:
>  	dma_free_coherent(plxdev->dma_dev.dev, ring_sz, plxdev->hw_ring,
>  			  plxdev->hw_ring_dma);
> @@ -454,7 +466,6 @@ static void plx_dma_free_chan_resources(struct dma_chan *chan)
>  	struct plx_dma_dev *plxdev = chan_to_plx_dma_dev(chan);
>  	size_t ring_sz = PLX_DMA_RING_COUNT * sizeof(*plxdev->hw_ring);
>  	int irq = -1;
> -	int i;
>
>  	spin_lock_bh(&plxdev->ring_lock);
>  	plxdev->ring_active = false;
> @@ -474,10 +485,7 @@ static void plx_dma_free_chan_resources(struct dma_chan *chan)
>
>  	plx_dma_abort_desc(plxdev);
>
> -	for (i = 0; i < PLX_DMA_RING_COUNT; i++)
> -		kfree(plxdev->desc_ring[i]);
> -
> -	kfree(plxdev->desc_ring);
> +	plx_dma_free_desc(plxdev);
>  	dma_free_coherent(plxdev->dma_dev.dev, ring_sz, plxdev->hw_ring,
>  			  plxdev->hw_ring_dma);
>
> --
> 2.47.3
>