[PATCH] char: hw_random: Fix a reference count leak.

[PATCH] char: hw_random: Fix a reference count leak.

[wu000273]

From: Qiushi Wu <wu000273@umn.edu>

Calling pm_runtime_get_sync increments the counter even in case of
failure, causing incorrect ref count if pm_runtime_put_sync is not
called in error handling paths. Thus replace the jump target
"err_pm_get" by "err_clock".

Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
Signed-off-by: Qiushi Wu <wu000273@umn.edu>
---
 drivers/char/hw_random/exynos-trng.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
index 8e1fe3f8dd2d..ffa7e0f061f0 100644
--- a/drivers/char/hw_random/exynos-trng.c
+++ b/drivers/char/hw_random/exynos-trng.c
@@ -135,7 +135,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
 	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Could not get runtime PM.\n");
-		goto err_pm_get;
+		goto err_clock;
 	}
 
 	trng->clk = devm_clk_get(&pdev->dev, "secss");
@@ -166,8 +166,6 @@ static int exynos_trng_probe(struct platform_device *pdev)
 
 err_clock:
 	pm_runtime_put_sync(&pdev->dev);
-
-err_pm_get:
 	pm_runtime_disable(&pdev->dev);
 
 	return ret;
-- 
2.17.1

Re: [PATCH] char: hw_random: Fix a reference count leak.

[Krzysztof Kozlowski]

On Sat, Jun 13, 2020 at 04:41:28PM -0500, wu000273@umn.edu wrote:
> From: Qiushi Wu <wu000273@umn.edu>
> 
> Calling pm_runtime_get_sync increments the counter even in case of
> failure, causing incorrect ref count if pm_runtime_put_sync is not
> called in error handling paths. Thus replace the jump target
> "err_pm_get" by "err_clock".
> 
> Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
> Signed-off-by: Qiushi Wu <wu000273@umn.edu>

1. Cc: <stable@vger.kernel.org>
2. Subject prefix:
	hwrng: exynos - 
3. Subject title: Fix PM runtime reference count leak
   (no need for end stop)

With these changes:
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>

Best regards,
Krzysztof

Re: [PATCH] char: hw_random: Fix a reference count leak.

[Lukasz Stelmach]

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It was <2020-06-13 sob 16:41>, when wu000273@umn.edu wrote:
> From: Qiushi Wu <wu000273@umn.edu>
>
> Calling pm_runtime_get_sync increments the counter even in case of
> failure, causing incorrect ref count if pm_runtime_put_sync is not
> called in error handling paths. Thus replace the jump target
> "err_pm_get" by "err_clock".
>
> Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
> Signed-off-by: Qiushi Wu <wu000273@umn.edu>
> ---
>  drivers/char/hw_random/exynos-trng.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
> index 8e1fe3f8dd2d..ffa7e0f061f0 100644
> --- a/drivers/char/hw_random/exynos-trng.c
> +++ b/drivers/char/hw_random/exynos-trng.c
> @@ -135,7 +135,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
>  	ret = pm_runtime_get_sync(&pdev->dev);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "Could not get runtime PM.\n");
> -		goto err_pm_get;
> +		goto err_clock;
>  	}
>  
>  	trng->clk = devm_clk_get(&pdev->dev, "secss");
> @@ -166,8 +166,6 @@ static int exynos_trng_probe(struct platform_device *pdev)
>  
>  err_clock:
>  	pm_runtime_put_sync(&pdev->dev);
> -
> -err_pm_get:
>  	pm_runtime_disable(&pdev->dev);
>  
>  	return ret;

I believe this fix has already been submitted

    https://lore.kernel.org/linux-arm-kernel/20200522011659.26727-1-dinghao.liu@zju.edu.cn/T/#u

It hasn't been applied though. Anyway, thank you for your work.

Herbert, could you take a look at the Dinghao's patch, please?
-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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Re: [PATCH] char: hw_random: Fix a reference count leak.

[Herbert Xu]

On Mon, Jun 15, 2020 at 03:18:54PM +0200, Lukasz Stelmach wrote:
>
> I believe this fix has already been submitted
> 
>     https://lore.kernel.org/linux-arm-kernel/20200522011659.26727-1-dinghao.liu@zju.edu.cn/T/#u
> 
> It hasn't been applied though. Anyway, thank you for your work.
> 
> Herbert, could you take a look at the Dinghao's patch, please?

It was part of a number of patches that did similar things.  The
general conclusion was that it should call put_noidle instead.

See

	https://patchwork.kernel.org/patch/11574843/

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt