[PATCH net] dpaa2-eth: fix memory leak in XDP_REDIRECT

From: Ioana Ciornei <ioana.ciornei@nxp.com>

If xdp_do_redirect() fails, the calling driver should handle recycling
or freeing of the page associated with the frame. The dpaa2-eth driver
didn't do either of them and just incremented a counter.
Fix this by trying to DMA map back the page and recycle it or, if the
mapping fails, just free it.

Fixes: d678be1dc1ec ("dpaa2-eth: add XDP_REDIRECT support")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
---
 drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index fb0bcd18ec0c..f1c2b3c7f7e9 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

@@ -399,10 +399,20 @@ static u32 dpaa2_eth_run_xdp(struct dpaa2_eth_priv *priv,
 		xdp.frame_sz = DPAA2_ETH_RX_BUF_RAW_SIZE;
 
 		err = xdp_do_redirect(priv->net_dev, &xdp, xdp_prog);
-		if (unlikely(err))
+		if (unlikely(err)) {
+			addr = dma_map_page(priv->net_dev->dev.parent,
+					    virt_to_page(vaddr), 0,
+					    priv->rx_buf_size, DMA_BIDIRECTIONAL);
+			if (unlikely(dma_mapping_error(priv->net_dev->dev.parent, addr))) {
+				free_pages((unsigned long)vaddr, 0);
+			} else {
+				ch->buf_count++;
+				dpaa2_eth_xdp_release_buf(priv, ch, addr);
+			}
 			ch->stats.xdp_drop++;
-		else
+		} else {
 			ch->stats.xdp_redirect++;
+		}
 		break;
 	}
 

-- 
2.30.0

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Thu, 11 Feb 2021 21:51:22 +0200 you wrote:

From: Ioana Ciornei <ioana.ciornei@nxp.com>

If xdp_do_redirect() fails, the calling driver should handle recycling
or freeing of the page associated with the frame. The dpaa2-eth driver
didn't do either of them and just incremented a counter.
Fix this by trying to DMA map back the page and recycle it or, if the
mapping fails, just free it.

[...]

Here is the summary with links:
  - [net] dpaa2-eth: fix memory leak in XDP_REDIRECT
    https://git.kernel.org/netdev/net/c/e12be9139cca

You are awesome, thank you!
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