From:   Johan Hovold <johan+linaro@kernel.org>
To:     Georgi Djakov <djakov@kernel.org>
Cc:     "Shawn Guo" <shawnguo@kernel.org>,
        "Sascha Hauer" <s.hauer@pengutronix.de>,
        "Pengutronix Kernel Team" <kernel@pengutronix.de>,
        "Fabio Estevam" <festevam@gmail.com>,
        "NXP Linux Team" <linux-imx@nxp.com>,
        "Andy Gross" <agross@kernel.org>,
        "Bjorn Andersson" <andersson@kernel.org>,
        "Konrad Dybcio" <konrad.dybcio@linaro.org>,
        "Sylwester Nawrocki" <s.nawrocki@samsung.com>,
        =?UTF-8?q?Artur=20=C5=9Awigo=C5=84?= <a.swigon@samsung.com>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski@linaro.org>,
        "Alim Akhtar" <alim.akhtar@samsung.com>,
        "Thierry Reding" <thierry.reding@gmail.com>,
        "Jonathan Hunter" <jonathanh@nvidia.com>, linux-pm@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-arm-msm@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
        Johan Hovold <johan+linaro@kernel.org>, stable@vger.kernel.org
Subject: [PATCH v2 15/23] interconnect: exynos: fix registration race
Date:   Mon,  6 Mar 2023 08:56:43 +0100
Message-Id: <20230306075651.2449-16-johan+linaro@kernel.org>
In-Reply-To: <20230306075651.2449-1-johan+linaro@kernel.org>
References: <20230306075651.2449-1-johan+linaro@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The current interconnect provider registration interface is inherently
racy as nodes are not added until the after adding the provider. This
can specifically cause racing DT lookups to trigger a NULL-pointer
deference when either a NULL pointer or not fully initialised node is
returned from exynos_generic_icc_xlate().

Switch to using the new API where the provider is not registered until
after it has been fully initialised.

Fixes: 2f95b9d5cf0b ("interconnect: Add generic interconnect driver for Exynos SoCs")
Cc: stable@vger.kernel.org      # 5.11
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/interconnect/samsung/exynos.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/interconnect/samsung/exynos.c b/drivers/interconnect/samsung/exynos.c
index e70665899482..72e42603823b 100644
--- a/drivers/interconnect/samsung/exynos.c
+++ b/drivers/interconnect/samsung/exynos.c
@@ -98,12 +98,13 @@ static int exynos_generic_icc_remove(struct platform_device *pdev)
 	struct exynos_icc_priv *priv = platform_get_drvdata(pdev);
 	struct icc_node *parent_node, *node = priv->node;
 
+	icc_provider_deregister(&priv->provider);
+
 	parent_node = exynos_icc_get_parent(priv->dev->parent->of_node);
 	if (parent_node && !IS_ERR(parent_node))
 		icc_link_destroy(node, parent_node);
 
 	icc_nodes_remove(&priv->provider);
-	icc_provider_del(&priv->provider);
 
 	return 0;
 }
@@ -132,15 +133,11 @@ static int exynos_generic_icc_probe(struct platform_device *pdev)
 	provider->inter_set = true;
 	provider->data = priv;
 
-	ret = icc_provider_add(provider);
-	if (ret < 0)
-		return ret;
+	icc_provider_init(provider);
 
 	icc_node = icc_node_create(pdev->id);
-	if (IS_ERR(icc_node)) {
-		ret = PTR_ERR(icc_node);
-		goto err_prov_del;
-	}
+	if (IS_ERR(icc_node))
+		return PTR_ERR(icc_node);
 
 	priv->node = icc_node;
 	icc_node->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
@@ -171,14 +168,17 @@ static int exynos_generic_icc_probe(struct platform_device *pdev)
 			goto err_pmqos_del;
 	}
 
+	ret = icc_provider_register(provider);
+	if (ret < 0)
+		goto err_pmqos_del;
+
 	return 0;
 
 err_pmqos_del:
 	dev_pm_qos_remove_request(&priv->qos_req);
 err_node_del:
 	icc_nodes_remove(provider);
-err_prov_del:
-	icc_provider_del(provider);
+
 	return ret;
 }
 
-- 
2.39.2