[PATCH v2] dmaengine: sun6i-dma: Fix memory leak in sun6i_dma_terminate_all

[PATCH v2] dmaengine: sun6i-dma: Fix memory leak in sun6i_dma_terminate_all

[Hongling Zeng]

When terminating a non-cyclic DMA transfer, the active descriptor
is not properly reclaimed. The descriptor is removed from the
desc_issued list in sun6i_dma_start_desc(), but in
sun6i_dma_terminate_all(), only cyclic transfer descriptors are
added to the desc_completed list before cleanup.

For non-cyclic transfers, pchan->desc is set to NULL without first
adding the descriptor back to a list that vchan_get_all_descriptors()
can collect. This causes the descriptor and its associated LLI chain
to be permanently leaked.

Fix by ensuring both cyclic and non-cyclic active descriptors are
added to the desc_completed list before setting pchan->desc to NULL.

Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller")
Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>

---
 Change in v2;
 -Add pchan->desc != pchan->done check to prevent race condition
  where completed descriptors could be double-added to desc_completed
  list, causing list corruption
---
 drivers/dma/sun6i-dma.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 7a79f346250a..12d038ef5f2e 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -946,16 +946,14 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan)
 
 	spin_lock_irqsave(&vchan->vc.lock, flags);
 
-	if (vchan->cyclic) {
-		vchan->cyclic = false;
-		if (pchan && pchan->desc) {
-			struct virt_dma_desc *vd = &pchan->desc->vd;
-			struct virt_dma_chan *vc = &vchan->vc;
+	if (pchan && pchan->desc && pchan->desc != pchan->done) {
+		struct virt_dma_desc *vd = &pchan->desc->vd;
+		struct virt_dma_chan *vc = &vchan->vc;
 
-			list_add_tail(&vd->node, &vc->desc_completed);
-		}
+		list_add_tail(&vd->node, &vc->desc_completed);
 	}
 
+	vchan->cyclic = false;
 	vchan_get_all_descriptors(&vchan->vc, &head);
 
 	if (pchan) {
-- 
2.25.1

Re: [PATCH v2] dmaengine: sun6i-dma: Fix memory leak in sun6i_dma_terminate_all

[Jernej Škrabec]

Dne torek, 16. junij 2026 ob 08:04:49 Srednjeevropski poletni čas je Hongling Zeng napisal(a):
> When terminating a non-cyclic DMA transfer, the active descriptor
> is not properly reclaimed. The descriptor is removed from the
> desc_issued list in sun6i_dma_start_desc(), but in
> sun6i_dma_terminate_all(), only cyclic transfer descriptors are
> added to the desc_completed list before cleanup.
> 
> For non-cyclic transfers, pchan->desc is set to NULL without first
> adding the descriptor back to a list that vchan_get_all_descriptors()
> can collect. This causes the descriptor and its associated LLI chain
> to be permanently leaked.
> 
> Fix by ensuring both cyclic and non-cyclic active descriptors are
> added to the desc_completed list before setting pchan->desc to NULL.
> 
> Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller")
> Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Best regards,
Jernej

> 
> ---
>  Change in v2;
>  -Add pchan->desc != pchan->done check to prevent race condition
>   where completed descriptors could be double-added to desc_completed
>   list, causing list corruption
> ---
>  drivers/dma/sun6i-dma.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index 7a79f346250a..12d038ef5f2e 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -946,16 +946,14 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan)
>  
>  	spin_lock_irqsave(&vchan->vc.lock, flags);
>  
> -	if (vchan->cyclic) {
> -		vchan->cyclic = false;
> -		if (pchan && pchan->desc) {
> -			struct virt_dma_desc *vd = &pchan->desc->vd;
> -			struct virt_dma_chan *vc = &vchan->vc;
> +	if (pchan && pchan->desc && pchan->desc != pchan->done) {
> +		struct virt_dma_desc *vd = &pchan->desc->vd;
> +		struct virt_dma_chan *vc = &vchan->vc;
>  
> -			list_add_tail(&vd->node, &vc->desc_completed);
> -		}
> +		list_add_tail(&vd->node, &vc->desc_completed);
>  	}
>  
> +	vchan->cyclic = false;
>  	vchan_get_all_descriptors(&vchan->vc, &head);
>  
>  	if (pchan) {
>