linux-kernel - [PATCH] The sun50i_iommu_of_xlate() function didn't properly handle the case where of_find_device_by_node() returns NULL. This could lead to a NULL pointer dereference when accessing platform_get_drvdata(iommu_pdev) if the device node couldn't be found.

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Message-ID: <tencent_889D023A2A9B04DE8D592DFE961C5893C706@qq.com>
Date: Tue, 24 Jun 2025 16:35:43 +0800
From: Zhang Shurong <zhang_shurong@...mail.com>
To: joro@...tes.org
Cc: will@...nel.org,
	robin.murphy@....com,
	wens@...e.org,
	jernej.skrabec@...il.com,
	samuel@...lland.org,
	iommu@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-sunxi@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Zhang Shurong <zhang_shurong@...mail.com>
Subject: [PATCH] The sun50i_iommu_of_xlate() function didn't properly handle the case where of_find_device_by_node() returns NULL. This could lead to a NULL pointer dereference when accessing platform_get_drvdata(iommu_pdev) if the device node couldn't be found.

Add a WARN_ON() check to detect this condition and return -ENODEV when it
occurs. This ensures proper error handling and helps diagnose incorrect
device tree configurations at runtime.

Fixes: 4100b8c229b3 ("iommu: Add Allwinner H6 IOMMU driver")
Signed-off-by: Zhang Shurong <zhang_shurong@...mail.com>
---
 drivers/iommu/sun50i-iommu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
index 76c9620af4bb..0f85850269ae 100644
--- a/drivers/iommu/sun50i-iommu.c
+++ b/drivers/iommu/sun50i-iommu.c
@@ -833,6 +833,9 @@ static int sun50i_iommu_of_xlate(struct device *dev,
 				 const struct of_phandle_args *args)
 {
 	struct platform_device *iommu_pdev = of_find_device_by_node(args->np);
+	if (WARN_ON(!iommu_pdev))
+		return -ENODEV;
+
 	unsigned id = args->args[0];
 
 	dev_iommu_priv_set(dev, platform_get_drvdata(iommu_pdev));
-- 
2.39.5