[PATCH v2] drm: fix a memleak on mutex failure path

[PATCH v2] drm: fix a memleak on mutex failure path

[green]

From: Oleg Drokin <green@linuxhacker.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@linuxhacker.ru>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 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

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

[Jani Nikula]

On Mon, 27 Apr 2015, green@linuxhacker.ru wrote:
> From: Oleg Drokin <green@linuxhacker.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@linuxhacker.ru>
> CC: Daniel Vetter <daniel.vetter@ffwll.ch>

Reviewed-by: Jani Nikula <jani.nikula@intel.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

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

[Daniel Vetter]

On Tue, Apr 28, 2015 at 10:25:46AM +0300, Jani Nikula wrote:
> On Mon, 27 Apr 2015, green@linuxhacker.ru wrote:
> > From: Oleg Drokin <green@linuxhacker.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@linuxhacker.ru>
> > CC: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>

Applied to topic/drm-misc, thanks.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch