[PATCH net v3] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval

[PATCH net v3] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval

[Abin Joseph]

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@amd.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com> 
---

Changes in v2:
Fix the alias to net

Changes in v3:
Remove unwanted space 
Add reviewed by tag

---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 0d8a05fe541a..ec6d47dc984a 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -1168,6 +1168,15 @@ static void axienet_dma_rx_cb(void *data, const struct dmaengine_result *result)
 						       &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 +1189,7 @@ 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

Re: [PATCH net v3] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval

[kernel test robot]

Hi,

Thanks for your patch.

FYI: kernel test robot notices the stable kernel rule is not satisfied.

The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1

Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree.
Subject: [PATCH net v3] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval
Link: https://lore.kernel.org/stable/20250903025213.3120181-1-abin.joseph%40amd.com

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Re: [PATCH net v3] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval

[patchwork-bot+netdevbpf]

Hello:

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

On Wed, 3 Sep 2025 08:22:13 +0530 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [net,v3] net: xilinx: axienet: Add error handling for RX metadata pointer retrieval
    https://git.kernel.org/netdev/net/c/8bbceba7dc50

You are awesome, thank you!
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