linux-kernel - Re: [PATCH v2] drm: fix a memleak on mutex failure path

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Message-ID: <87h9s0btol.fsf@intel.com>
Date:	Tue, 28 Apr 2015 10:25:46 +0300
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	green@...uxhacker.ru, David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org
Cc:	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
	Oleg Drokin <green@...uxhacker.ru>,
	Daniel Vetter <daniel.vetter@...ll.ch>
Subject: Re: [PATCH v2] drm: fix a memleak on mutex failure path

On Mon, 27 Apr 2015, green@...uxhacker.ru wrote:
> From: Oleg Drokin <green@...uxhacker.ru>
>
> Need to free just allocated ctx allocation if we cannot
> get our config mutex.
>
> This one has been flagged by kbuild bot all the way back in August,
> but somehow nobody picked it up:
> https://lists.01.org/pipermail/kbuild/2014-August/001691.html
>
> In addition there is another failure path that leaks the same
> ctx reference that is fixed.
>
> Found with smatch.
>
> Signed-off-by: Oleg Drokin <green@...uxhacker.ru>
> CC: Daniel Vetter <daniel.vetter@...ll.ch>

Reviewed-by: Jani Nikula <jani.nikula@...el.com>


> ---
>  drivers/gpu/drm/drm_modeset_lock.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
> index 51cc47d..c0a5cd8 100644
> --- a/drivers/gpu/drm/drm_modeset_lock.c
> +++ b/drivers/gpu/drm/drm_modeset_lock.c
> @@ -80,8 +80,10 @@ int __drm_modeset_lock_all(struct drm_device *dev,
>  		return -ENOMEM;
>  
>  	if (trylock) {
> -		if (!mutex_trylock(&config->mutex))
> -			return -EBUSY;
> +		if (!mutex_trylock(&config->mutex)) {
> +			ret = -EBUSY;
> +			goto out;
> +		}
>  	} else {
>  		mutex_lock(&config->mutex);
>  	}
> @@ -114,6 +116,8 @@ fail:
>  		goto retry;
>  	}
>  
> +out:
> +	kfree(ctx);
>  	return ret;
>  }
>  EXPORT_SYMBOL(__drm_modeset_lock_all);
> -- 
> 2.1.0
>

-- 
Jani Nikula, Intel Open Source Technology Center
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