[PATCH net] net/mlx5e: Fix AF_XDP TX timestamp teardown NULL dereference

[PATCH net] net/mlx5e: Fix AF_XDP TX timestamp teardown NULL dereference

[prathameshdeshpande7]

From: Prathamesh Deshpande <prathameshdeshpande7@gmail.com>

During XSK TX queue teardown, outstanding descriptors are completed
without a CQE. If one requested a TX timestamp, the completion path
passes that NULL CQE to mlx5e_xsk_fill_timestamp(), which dereferences
it.

Return zero when no CQE is available, indicating that teardown did not
produce a TX timestamp.

Fixes: ec706a860eba ("net/mlx5e: Implement AF_XDP TX timestamp and checksum offload")

Signed-off-by: Prathamesh Deshpande <prathameshdeshpande7@gmail.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
index 77ea51bfbaae..2cca20e1b9b7 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
@@ -293,6 +293,9 @@ static u64 mlx5e_xsk_fill_timestamp(void *_priv)
 	struct mlx5e_xsk_tx_complete *priv = _priv;
 	u64 ts;
 
+	if (!priv->cqe)
+		return 0;
+
 	ts = get_cqe_ts(priv->cqe);
 
 	if (mlx5_is_real_time_rq(priv->cq->mdev) || mlx5_is_real_time_sq(priv->cq->mdev))
-- 
2.43.0

Re: [PATCH net] net/mlx5e: Fix AF_XDP TX timestamp teardown NULL dereference

[Tariq Toukan]

On 26/09/2026 19:53, prathameshdeshpande7@gmail.com wrote:
> From: Prathamesh Deshpande <prathameshdeshpande7@gmail.com>
> 
> During XSK TX queue teardown, outstanding descriptors are completed
> without a CQE. If one requested a TX timestamp, the completion path
> passes that NULL CQE to mlx5e_xsk_fill_timestamp(), which dereferences
> it.
> 
> Return zero when no CQE is available, indicating that teardown did not
> produce a TX timestamp.
> 
> Fixes: ec706a860eba ("net/mlx5e: Implement AF_XDP TX timestamp and checksum offload")
> 
> Signed-off-by: Prathamesh Deshpande <prathameshdeshpande7@gmail.com>
> ---
>   drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> index 77ea51bfbaae..2cca20e1b9b7 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> @@ -293,6 +293,9 @@ static u64 mlx5e_xsk_fill_timestamp(void *_priv)
>   	struct mlx5e_xsk_tx_complete *priv = _priv;
>   	u64 ts;
>   
> +	if (!priv->cqe)
> +		return 0;
> +
>   	ts = get_cqe_ts(priv->cqe);
>   
>   	if (mlx5_is_real_time_rq(priv->cq->mdev) || mlx5_is_real_time_sq(priv->cq->mdev))


Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Thanks.

Re: [PATCH net] net/mlx5e: Fix AF_XDP TX timestamp teardown NULL dereference

[patchwork-bot+netdevbpf]

Hello:

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

On Sat, 26 Sep 2026 17:53:57 +0100 you wrote:
> From: Prathamesh Deshpande <prathameshdeshpande7@gmail.com>
> 
> During XSK TX queue teardown, outstanding descriptors are completed
> without a CQE. If one requested a TX timestamp, the completion path
> passes that NULL CQE to mlx5e_xsk_fill_timestamp(), which dereferences
> it.
> 
> [...]

Here is the summary with links:
  - [net] net/mlx5e: Fix AF_XDP TX timestamp teardown NULL dereference
    https://git.kernel.org/netdev/net/c/7b97273cbebe

You are awesome, thank you!
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