linux-kernel - Re: [PATCH] power: sequencing: fix NULL-pointer dereference in error path

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Message-ID: <7d7dcc46-2042-439b-a744-49ae4b507839@suswa.mountain>
Date: Fri, 12 Jul 2024 09:59:06 -0500
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Krzysztof Kozlowski <krzk@...nel.org>, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH] power: sequencing: fix NULL-pointer dereference in error
 path

On Fri, Jul 12, 2024 at 04:45:46PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> We may call pwrseq_target_free() on a target without the final unit
> assigned yet. In this case pwrseq_unit_put() will dereference
> a NULL-pointer. Add a check to the latter function.
> 
> Fixes: 249ebf3f65f8 ("power: sequencing: implement the pwrseq core")
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/linux-pm/62a3531e-9927-40f8-b587-254a2dfa47ef@stanley.mountain/
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  drivers/power/sequencing/core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/power/sequencing/core.c b/drivers/power/sequencing/core.c
> index 9c32b07a55e7..fe07100e4b33 100644
> --- a/drivers/power/sequencing/core.c
> +++ b/drivers/power/sequencing/core.c
> @@ -119,7 +119,8 @@ static void pwrseq_unit_release(struct kref *ref);
>  
>  static void pwrseq_unit_put(struct pwrseq_unit *unit)
>  {
> -	kref_put(&unit->ref, pwrseq_unit_release);
> +	if (unit)

I was wondering where you would put the check.  But it needs to be:

	if (!IS_ERR_OR_NULL(unit))

regards,
dan carpenter

> +		kref_put(&unit->ref, pwrseq_unit_release);
>  }
>  
>  /**
> -- 
> 2.43.0