[PATCH v2] pwm: img: Fix null pointer access in probe

[PATCH v2] pwm: img: Fix null pointer access in probe

[Hauke Mehrtens]

dev_get_drvdata() is called in img_pwm_runtime_resume() before the
driver data is set.
When pm_runtime_enabled() returns false in img_pwm_probe() it calls
img_pwm_runtime_resume() which results in a null pointer access.

This patch fixes the problem by setting the driver data earlier in the
img_pwm_probe() function.

This crash was seen when booting the Imagination Technologies Creator
Ci40 (Marduk) with kernel 5.4 in OpenWrt.

Fixes: e690ae526216 ("pwm: img: Add runtime PM")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/pwm/pwm-img.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-img.c b/drivers/pwm/pwm-img.c
index 599a0f66a384..a34d95ed70b2 100644
--- a/drivers/pwm/pwm-img.c
+++ b/drivers/pwm/pwm-img.c
@@ -277,6 +277,8 @@ static int img_pwm_probe(struct platform_device *pdev)
 		return PTR_ERR(pwm->pwm_clk);
 	}
 
+	platform_set_drvdata(pdev, pwm);
+
 	pm_runtime_set_autosuspend_delay(&pdev->dev, IMG_PWM_PM_TIMEOUT);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
@@ -313,7 +315,6 @@ static int img_pwm_probe(struct platform_device *pdev)
 		goto err_suspend;
 	}
 
-	platform_set_drvdata(pdev, pwm);
 	return 0;
 
 err_suspend:
-- 
2.20.1

Re: [PATCH v2] pwm: img: Fix null pointer access in probe

[Thierry Reding]

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On Thu, Aug 20, 2020 at 07:14:25PM +0200, Hauke Mehrtens wrote:
> dev_get_drvdata() is called in img_pwm_runtime_resume() before the
> driver data is set.
> When pm_runtime_enabled() returns false in img_pwm_probe() it calls
> img_pwm_runtime_resume() which results in a null pointer access.
> 
> This patch fixes the problem by setting the driver data earlier in the
> img_pwm_probe() function.
> 
> This crash was seen when booting the Imagination Technologies Creator
> Ci40 (Marduk) with kernel 5.4 in OpenWrt.
> 
> Fixes: e690ae526216 ("pwm: img: Add runtime PM")
> Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
> Acked-by: Lee Jones <lee.jones@linaro.org>
> ---
>  drivers/pwm/pwm-img.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Applied, thanks.

Thierry

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