[PATCH] net/ftgmac100: fix ring allocation unwind leaks on open failure

[PATCH] net/ftgmac100: fix ring allocation unwind leaks on open failure

[Yufan Chen]

From: Yufan Chen <ericterminal@gmail.com>

ftgmac100_alloc_rings() allocated rx_skbs, tx_skbs, rxdes, txdes, and rx_scratch in stages but returned directly on any intermediate allocation failure. This left previously allocated objects unreleased and could accumulate leaks across repeated ifup retries under memory pressure.

Switch ftgmac100_alloc_rings() to a centralized goto-based unwind path that calls ftgmac100_free_rings() on failure so partially allocated ring resources are always released before returning -ENOMEM.

Also clear rx_skbs, tx_skbs, and rx_scratch pointers in ftgmac100_free_rings() after freeing. This prevents stale pointers from being reused during later retry failures and keeps ring teardown idempotent.

Signed-off-by: Yufan Chen <ericterminal@gmail.com>
---
 drivers/net/ethernet/faraday/ftgmac100.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
index 1e91e79c8..147300e60 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -946,7 +946,9 @@ static void ftgmac100_free_rings(struct ftgmac100 *priv)
 {
 	/* Free skb arrays */
 	kfree(priv->rx_skbs);
+	priv->rx_skbs = NULL;
 	kfree(priv->tx_skbs);
+	priv->tx_skbs = NULL;
 
 	/* Free descriptors */
 	if (priv->rxdes)
@@ -965,31 +967,34 @@ static void ftgmac100_free_rings(struct ftgmac100 *priv)
 	if (priv->rx_scratch)
 		dma_free_coherent(priv->dev, RX_BUF_SIZE,
 				  priv->rx_scratch, priv->rx_scratch_dma);
+	priv->rx_scratch = NULL;
 }
 
 static int ftgmac100_alloc_rings(struct ftgmac100 *priv)
 {
+	int err = -ENOMEM;
+
 	/* Allocate skb arrays */
 	priv->rx_skbs = kcalloc(MAX_RX_QUEUE_ENTRIES, sizeof(void *),
 				GFP_KERNEL);
 	if (!priv->rx_skbs)
-		return -ENOMEM;
+		goto out;
 	priv->tx_skbs = kcalloc(MAX_TX_QUEUE_ENTRIES, sizeof(void *),
 				GFP_KERNEL);
 	if (!priv->tx_skbs)
-		return -ENOMEM;
+		goto out;
 
 	/* Allocate descriptors */
 	priv->rxdes = dma_alloc_coherent(priv->dev,
 					 MAX_RX_QUEUE_ENTRIES * sizeof(struct ftgmac100_rxdes),
 					 &priv->rxdes_dma, GFP_KERNEL);
 	if (!priv->rxdes)
-		return -ENOMEM;
+		goto out;
 	priv->txdes = dma_alloc_coherent(priv->dev,
 					 MAX_TX_QUEUE_ENTRIES * sizeof(struct ftgmac100_txdes),
 					 &priv->txdes_dma, GFP_KERNEL);
 	if (!priv->txdes)
-		return -ENOMEM;
+		goto out;
 
 	/* Allocate scratch packet buffer */
 	priv->rx_scratch = dma_alloc_coherent(priv->dev,
@@ -997,9 +1002,13 @@ static int ftgmac100_alloc_rings(struct ftgmac100 *priv)
 					      &priv->rx_scratch_dma,
 					      GFP_KERNEL);
 	if (!priv->rx_scratch)
-		return -ENOMEM;
+		goto out;
 
 	return 0;
+
+out:
+	ftgmac100_free_rings(priv);
+	return err;
 }
 
 static void ftgmac100_init_rings(struct ftgmac100 *priv)
-- 
2.47.3

Re: [PATCH] net/ftgmac100: fix ring allocation unwind leaks on open failure

[Andrew Lunn]

On Sat, Mar 28, 2026 at 05:24:28PM +0800, Yufan Chen wrote:
> From: Yufan Chen <ericterminal@gmail.com>
> 
> ftgmac100_alloc_rings() allocated rx_skbs, tx_skbs, rxdes, txdes, and rx_scratch in stages but returned directly on any intermediate allocation failure. This left previously allocated objects unreleased and could accumulate leaks across repeated ifup retries under memory pressure.

Please take a read of

https://docs.kernel.org/process/submitting-patches.html

and

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html


You have a number of process issues.

>  static int ftgmac100_alloc_rings(struct ftgmac100 *priv)
>  {
> +	int err = -ENOMEM;
> +
>  	/* Allocate skb arrays */
>  	priv->rx_skbs = kcalloc(MAX_RX_QUEUE_ENTRIES, sizeof(void *),
>  				GFP_KERNEL);
>  	if (!priv->rx_skbs)
> -		return -ENOMEM;
> +		goto out;
>  	priv->tx_skbs = kcalloc(MAX_TX_QUEUE_ENTRIES, sizeof(void *),
>  				GFP_KERNEL);
>  	if (!priv->tx_skbs)
> -		return -ENOMEM;
> +		goto out;
>  
>  	/* Allocate descriptors */
>  	priv->rxdes = dma_alloc_coherent(priv->dev,
>  					 MAX_RX_QUEUE_ENTRIES * sizeof(struct ftgmac100_rxdes),
>  					 &priv->rxdes_dma, GFP_KERNEL);
>  	if (!priv->rxdes)
> -		return -ENOMEM;
> +		goto out;
>  	priv->txdes = dma_alloc_coherent(priv->dev,
>  					 MAX_TX_QUEUE_ENTRIES * sizeof(struct ftgmac100_txdes),
>  					 &priv->txdes_dma, GFP_KERNEL);
>  	if (!priv->txdes)
> -		return -ENOMEM;
> +		goto out;
>  
>  	/* Allocate scratch packet buffer */
>  	priv->rx_scratch = dma_alloc_coherent(priv->dev,
> @@ -997,9 +1002,13 @@ static int ftgmac100_alloc_rings(struct ftgmac100 *priv)
>  					      &priv->rx_scratch_dma,
>  					      GFP_KERNEL);
>  	if (!priv->rx_scratch)
> -		return -ENOMEM;
> +		goto out;
>  
>  	return 0;
> +
> +out:
> +	ftgmac100_free_rings(priv);
> +	return err;

If you look at other drivers, you will notice that functions that do
allocations pretty much always do their own cleanup, rather than
calling a helper. You generally see multiple labels, one per
allocation, and gotos jumping to the needed code.

    Andrew

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