linux-kernel - [PATCH net v2] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval

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Message-ID: <20250902013205.2849707-1-abin.joseph@amd.com>
Date: Tue, 2 Sep 2025 07:02:05 +0530
From: Abin Joseph <abin.joseph@....com>
To: <radhey.shyam.pandey@....com>, <andrew+netdev@...n.ch>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <michal.simek@....com>
CC: <git@....com>, <abin.joseph@....com>, <netdev@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<stable@...r.kernel.org>
Subject: [PATCH net v2] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval

Add proper error checking for dmaengine_desc_get_metadata_ptr() which
can return an error pointer and lead to potential crashes or undefined
behaviour if the pointer retrieval fails.

Properly handle the error by unmapping DMA buffer, freeing the skb and
returning early to prevent further processing with invalid data.

Fixes: 6a91b846af85 ("net: axienet: Introduce dmaengine support")
Signed-off-by: Abin Joseph <abin.joseph@....com>
---

Changes in v2:
Update the alias to net

---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 0d8a05fe541a..83469f7f08d1 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -1166,8 +1166,18 @@ static void axienet_dma_rx_cb(void *data, const struct dmaengine_result *result)
 	skb = skbuf_dma->skb;
 	app_metadata = dmaengine_desc_get_metadata_ptr(skbuf_dma->desc, &meta_len,
 						       &meta_max_len);
+
 	dma_unmap_single(lp->dev, skbuf_dma->dma_address, lp->max_frm_size,
 			 DMA_FROM_DEVICE);
+
+	if (IS_ERR(app_metadata)) {
+		if (net_ratelimit())
+			netdev_err(lp->ndev, "Failed to get RX metadata pointer\n");
+		dev_kfree_skb_any(skb);
+		lp->ndev->stats.rx_dropped++;
+		goto rx_submit;
+	}
+
 	/* TODO: Derive app word index programmatically */
 	rx_len = (app_metadata[LEN_APP] & 0xFFFF);
 	skb_put(skb, rx_len);
@@ -1180,6 +1190,7 @@ static void axienet_dma_rx_cb(void *data, const struct dmaengine_result *result)
 	u64_stats_add(&lp->rx_bytes, rx_len);
 	u64_stats_update_end(&lp->rx_stat_sync);
 
+rx_submit:
 	for (i = 0; i < CIRC_SPACE(lp->rx_ring_head, lp->rx_ring_tail,
 				   RX_BUF_NUM_DEFAULT); i++)
 		axienet_rx_submit_desc(lp->ndev);
-- 
2.34.1