Re: [RFC PATCH 03/13] staging: mmal-vchiq: Fix memory leak in error path

[Andrzej Pietrasiewicz <andrzej.p@collabora.com>]

Hi Maarten,

W dniu 3.03.2024 o 16:09, Maarten Vanraes pisze:
> From: Dave Stevenson <dave.stevenson@raspberrypi.org>
> 
> On error, vchiq_mmal_component_init could leave the
> event context allocated for ports.
> Clean them up in the error path.
> 
> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
> 
> staging: mmal-vchiq: Free the event context for control ports
> 
> vchiq_mmal_component_init calls init_event_context for the
> control port, but vchiq_mmal_component_finalise didn't free
> it, causing a memory leak..
> 
> Add the free call.
> 
> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
> Signed-off-by: Maarten Vanraes <maarten@rmail.be>
> ---
>   .../vc04_services/vchiq-mmal/mmal-vchiq.c     | 29 ++++++++++++++-----
>   1 file changed, 22 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c b/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c
> index 2e616604943d..1209b7db8f30 100644
> --- a/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c
> +++ b/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c
> @@ -1825,9 +1825,26 @@ static void free_event_context(struct vchiq_mmal_port *port)
>   {
>   	struct mmal_msg_context *ctx = port->event_context;
>   
> +	if (!ctx)
> +		return;
> +
>   	kfree(ctx->u.bulk.buffer->buffer);
>   	kfree(ctx->u.bulk.buffer);
>   	release_msg_context(ctx);
> +	port->event_context = NULL;
> +}
> +
> +static void release_all_event_contexts(struct vchiq_mmal_component *component)
> +{
> +	int idx;
> +
> +	for (idx = 0; idx < component->inputs; idx++)
> +		free_event_context(&component->input[idx]);
> +	for (idx = 0; idx < component->outputs; idx++)
> +		free_event_context(&component->output[idx]);
> +	for (idx = 0; idx < component->clocks; idx++)
> +		free_event_context(&component->clock[idx]);
> +	free_event_context(&component->control);
>   }
>   
>   /* Initialise a mmal component and its ports
> @@ -1925,6 +1942,7 @@ int vchiq_mmal_component_init(struct vchiq_mmal_instance *instance,
>   
>   release_component:
>   	destroy_component(instance, component);
> +	release_all_event_contexts(component);
>   unlock:
>   	if (component)
>   		component->in_use = false;
> @@ -1940,7 +1958,7 @@ EXPORT_SYMBOL_GPL(vchiq_mmal_component_init);
>   int vchiq_mmal_component_finalise(struct vchiq_mmal_instance *instance,
>   				  struct vchiq_mmal_component *component)
>   {
> -	int ret, idx;
> +	int ret;
>   
>   	if (mutex_lock_interruptible(&instance->vchiq_mutex))
>   		return -EINTR;
> @@ -1952,12 +1970,9 @@ int vchiq_mmal_component_finalise(struct vchiq_mmal_instance *instance,
>   
>   	component->in_use = false;
>   
> -	for (idx = 0; idx < component->inputs; idx++)
> -		free_event_context(&component->input[idx]);
> -	for (idx = 0; idx < component->outputs; idx++)
> -		free_event_context(&component->output[idx]);
> -	for (idx = 0; idx < component->clocks; idx++)
> -		free_event_context(&component->clock[idx]);
> +	release_all_event_contexts(component);

The way I understand this chunk is that you factor out the 3 "for" loops into
the new function "release_all_event_contexts()", because it is then reused 
elsewhere. "release_all_event_contexts()" already contains invocation of
"free_event_context(&component->control)"...

> +
> +	free_event_context(&component->control);

... but it is repeated here. Why?

Regards,

Andrzej

>   
>   	mutex_unlock(&instance->vchiq_mutex);
>