tegra_ahb_enable_smmu() utilizes driver_find_device_by_of_node() which
internally calls driver_find_device() to locate the matching device.
driver_find_device() increments the ref count of the found device by
calling get_device(), but tegra_ahb_enable_smmu() fails to call
put_device() to decrement the reference count before returning. This
results in a reference count leak of the device, which may prevent the
device from being properly released and cause a memory leak.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 89c788bab1f0 ("ARM: tegra: Add SMMU enabler in AHB")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
 drivers/amba/tegra-ahb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/amba/tegra-ahb.c b/drivers/amba/tegra-ahb.c
index f23c3ed01810..3ed5cef34806 100644
--- a/drivers/amba/tegra-ahb.c
+++ b/drivers/amba/tegra-ahb.c
@@ -148,6 +148,7 @@ int tegra_ahb_enable_smmu(struct device_node *dn)
 	val = gizmo_readl(ahb, AHB_ARBITRATION_XBAR_CTRL);
 	val |= AHB_ARBITRATION_XBAR_CTRL_SMMU_INIT_DONE;
 	gizmo_writel(ahb, val, AHB_ARBITRATION_XBAR_CTRL);
+	put_device(dev);
 	return 0;
 }
 EXPORT_SYMBOL(tegra_ahb_enable_smmu);
-- 
2.17.1

On 14/12/2025 12:53, Ma Ke wrote:
> tegra_ahb_enable_smmu() utilizes driver_find_device_by_of_node() which
> internally calls driver_find_device() to locate the matching device.
> driver_find_device() increments the ref count of the found device by
> calling get_device(), but tegra_ahb_enable_smmu() fails to call
> put_device() to decrement the reference count before returning. This
> results in a reference count leak of the device, which may prevent the
> device from being properly released and cause a memory leak.
> 
> Found by code review.
> 
> Cc: stable@vger.kernel.org
> Fixes: 89c788bab1f0 ("ARM: tegra: Add SMMU enabler in AHB")
> Signed-off-by: Ma Ke <make24@iscas.ac.cn>
> ---
>   drivers/amba/tegra-ahb.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/amba/tegra-ahb.c b/drivers/amba/tegra-ahb.c
> index f23c3ed01810..3ed5cef34806 100644
> --- a/drivers/amba/tegra-ahb.c
> +++ b/drivers/amba/tegra-ahb.c
> @@ -148,6 +148,7 @@ int tegra_ahb_enable_smmu(struct device_node *dn)
>   	val = gizmo_readl(ahb, AHB_ARBITRATION_XBAR_CTRL);
>   	val |= AHB_ARBITRATION_XBAR_CTRL_SMMU_INIT_DONE;
>   	gizmo_writel(ahb, val, AHB_ARBITRATION_XBAR_CTRL);
> +	put_device(dev);
>   	return 0;
>   }
>   EXPORT_SYMBOL(tegra_ahb_enable_smmu);


This has already been fixed and so this change is not needed.

-- 
nvpublic