[PATCH] net/mlx5: fix null derefrence in mlx5 txq start

[PATCH] net/mlx5: fix null derefrence in mlx5 txq start

[Weiguo Li]

Pointer 'txq_ctrl' was dereferenced and then compared to NULL.
Change the order to keep the logic consistent.

Fixes: f49f44839df3 ("net/mlx5: share Tx control code")
Cc: stable@dpdk.org

Signed-off-by: Weiguo Li <liweiguo@xencore.cn>
---
 drivers/net/mlx5/mlx5_trigger.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5_trigger.c b/drivers/net/mlx5/mlx5_trigger.c
index 7bdb897612..0741bf627d 100644
--- a/drivers/net/mlx5/mlx5_trigger.c
+++ b/drivers/net/mlx5/mlx5_trigger.c
@@ -54,11 +54,14 @@ mlx5_txq_start(struct rte_eth_dev *dev)
 
 	for (i = 0; i != priv->txqs_n; ++i) {
 		struct mlx5_txq_ctrl *txq_ctrl = mlx5_txq_get(dev, i);
-		struct mlx5_txq_data *txq_data = &txq_ctrl->txq;
+		struct mlx5_txq_data *txq_data;
 		uint32_t flags = MLX5_MEM_RTE | MLX5_MEM_ZERO;
 
 		if (!txq_ctrl)
 			continue;
+
+		txq_data = &txq_ctrl->txq;
+
 		if (!txq_ctrl->is_hairpin)
 			txq_alloc_elts(txq_ctrl);
 		MLX5_ASSERT(!txq_ctrl->obj);
-- 
2.34.1

RE: [PATCH] net/mlx5: fix null derefrence in mlx5 txq start

[Slava Ovsiienko]

Hi, Weiguo

Do we have some compiler's or linter's warning about the "dereference" ?
Actually it is not an issue, once we get txq_data pointer - the NULL is just added
with some offset, and there is pre-check before using the pointer.

And, please fix the typo in title  - "derefErence".

With best regards,
Slava

> -----Original Message-----
> From: Weiguo Li <liwg06@foxmail.com>
> Sent: Saturday, November 4, 2023 6:06 AM
> To: Michael Baum <michaelba@nvidia.com>
> Cc: Matan Azrad <matan@nvidia.com>; dev@dpdk.org; stable@dpdk.org;
> Weiguo Li <liweiguo@xencore.cn>
> Subject: [PATCH] net/mlx5: fix null derefrence in mlx5 txq start
> 
> Pointer 'txq_ctrl' was dereferenced and then compared to NULL.
> Change the order to keep the logic consistent.
> 
> Fixes: f49f44839df3 ("net/mlx5: share Tx control code")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Weiguo Li <liweiguo@xencore.cn>
> ---
>  drivers/net/mlx5/mlx5_trigger.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/mlx5/mlx5_trigger.c
> b/drivers/net/mlx5/mlx5_trigger.c index 7bdb897612..0741bf627d 100644
> --- a/drivers/net/mlx5/mlx5_trigger.c
> +++ b/drivers/net/mlx5/mlx5_trigger.c
> @@ -54,11 +54,14 @@ mlx5_txq_start(struct rte_eth_dev *dev)
> 
>  	for (i = 0; i != priv->txqs_n; ++i) {
>  		struct mlx5_txq_ctrl *txq_ctrl = mlx5_txq_get(dev, i);
> -		struct mlx5_txq_data *txq_data = &txq_ctrl->txq;
> +		struct mlx5_txq_data *txq_data;
>  		uint32_t flags = MLX5_MEM_RTE | MLX5_MEM_ZERO;
> 
>  		if (!txq_ctrl)
>  			continue;
> +
> +		txq_data = &txq_ctrl->txq;
> +
>  		if (!txq_ctrl->is_hairpin)
>  			txq_alloc_elts(txq_ctrl);
>  		MLX5_ASSERT(!txq_ctrl->obj);
> --
> 2.34.1