net/mlx5_core: Add error handling inmlx5_query_nic_vport_qkey_viol_cntr()

The function mlx5_query_nic_vport_qkey_viol_cntr() calls the function
mlx5_query_nic_vport_context() but does not check its return value. This
could lead to undefined behavior if the query fails. A proper
implementation can be found in mlx5_nic_vport_query_local_lb().

Add error handling for mlx5_query_nic_vport_context(). If it fails, free
the out buffer via kvfree() and return error code.

Fixes: 9efa752 ("net/mlx5_core: Introduce access functions to query vport RoCE fields")
Cc: stable@vger.kernel.org # v4.5
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20250521133620.912-1-vulab@iscas.ac.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: ISCAS-Vulab

drivers/net/ethernet/mellanox/mlx5/core/vport.c

@@ -519,19 +519,22 @@ int mlx5_query_nic_vport_qkey_viol_cntr(struct mlx5_core_dev *mdev,
 {
 	u32 *out;
 	int outlen = MLX5_ST_SZ_BYTES(query_nic_vport_context_out);
+	int err;
 
 	out = kvzalloc(outlen, GFP_KERNEL);
 	if (!out)
 		return -ENOMEM;
 
-	mlx5_query_nic_vport_context(mdev, 0, out);
+	err = mlx5_query_nic_vport_context(mdev, 0, out);
+	if (err)
+		goto out;
 
 	*qkey_viol_cntr = MLX5_GET(query_nic_vport_context_out, out,
 				   nic_vport_context.qkey_violation_counter);
-
+out:
 	kvfree(out);
 
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL_GPL(mlx5_query_nic_vport_qkey_viol_cntr);