When fail to dma_map_single() in mtk_rx_alloc(), it returns directly.
But the memory allocated for local variable data is not freed, and
local variabel data has not been attached to ring->data[i] yet, so the
memory allocated for local variable data will not be freed outside
mtk_rx_alloc() too. Thus memory leak would occur in this scenario.

Add skb_free_frag(data) when dma_map_single() failed.

Fixes: 23233e577ef9 ("net: ethernet: mtk_eth_soc: rely on page_pool for single page buffers")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 7cd381530aa4..bc47ef1e4dd5 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -2378,8 +2378,10 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 				data + NET_SKB_PAD + eth->ip_align,
 				ring->buf_size, DMA_FROM_DEVICE);
 			if (unlikely(dma_mapping_error(eth->dma_dev,
-						       dma_addr)))
+						       dma_addr))) {
+				skb_free_frag(data);
 				return -ENOMEM;
+			}
 		}
 		rxd->rxd1 = (unsigned int)dma_addr;
 		ring->data[i] = data;
-- 
2.25.1

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Sun, 20 Nov 2022 11:54:05 +0800 you wrote:
> When fail to dma_map_single() in mtk_rx_alloc(), it returns directly.
> But the memory allocated for local variable data is not freed, and
> local variabel data has not been attached to ring->data[i] yet, so the
> memory allocated for local variable data will not be freed outside
> mtk_rx_alloc() too. Thus memory leak would occur in this scenario.
> 
> Add skb_free_frag(data) when dma_map_single() failed.
> 
> [...]

Here is the summary with links:
  - [net] net: ethernet: mtk_eth_soc: fix potential memory leak in mtk_rx_alloc()
    https://git.kernel.org/netdev/net/c/3213f808ae21

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

> When fail to dma_map_single() in mtk_rx_alloc(), it returns directly.
> But the memory allocated for local variable data is not freed, and
> local variabel data has not been attached to ring->data[i] yet, so the
> memory allocated for local variable data will not be freed outside
> mtk_rx_alloc() too. Thus memory leak would occur in this scenario.
> 
> Add skb_free_frag(data) when dma_map_single() failed.
> 
> Fixes: 23233e577ef9 ("net: ethernet: mtk_eth_soc: rely on page_pool for single page buffers")
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Acked-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>

> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index 7cd381530aa4..bc47ef1e4dd5 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -2378,8 +2378,10 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
>  				data + NET_SKB_PAD + eth->ip_align,
>  				ring->buf_size, DMA_FROM_DEVICE);
>  			if (unlikely(dma_mapping_error(eth->dma_dev,
> -						       dma_addr)))
> +						       dma_addr))) {
> +				skb_free_frag(data);
>  				return -ENOMEM;
> +			}
>  		}
>  		rxd->rxd1 = (unsigned int)dma_addr;
>  		ring->data[i] = data;
> -- 
> 2.25.1
>