Re: [PATCH] media: v4l2-core: Fix a potential resource leak in v4l2_fwnode_parse_link()

[Christophe JAILLET]

Le 13/06/2023 à 12:55, Sakari Ailus a écrit :
> Hi Christophe,
>
> On Mon, May 29, 2023 at 08:17:18AM +0200, Christophe JAILLET wrote:
> > 'fwnode is known to be NULL, at this point, so fwnode_handle_put() is a
> > no-op.
> >
> > Release the reference taken from a previous fwnode_graph_get_port_parent()
> > call instead.
> >
> > Fixes: ca50c197bd96 ("[media] v4l: fwnode: Support generic fwnode for parsing standardised properties")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> > /!\  THIS PATCH IS SPECULATIVE  /!\
> >           review with care
> > ---
> >   drivers/media/v4l2-core/v4l2-fwnode.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > index 049c2f2001ea..b7dd467c53fd 100644
> > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > @@ -571,7 +571,7 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> >   
> >   	fwnode = fwnode_graph_get_remote_endpoint(fwnode);
> >   	if (!fwnode) {
> > -		fwnode_handle_put(fwnode);
> > +		fwnode_handle_put(link->local_node);
>
> link->local_node also needs to be non-NULL for the successful case. The
> condition should take that into account. Could you send v2 with that?
>
> >   		return -ENOLINK;
> >   	}
> >   

Hi,
something like below?

@@ -568,19 +568,25 @@ int v4l2_fwnode_parse_link(struct fwnode_handle 
*fwnode,
 	link->local_id = fwep.id;
 	link->local_port = fwep.port;
 	link->local_node = fwnode_graph_get_port_parent(fwnode);
+	if (!link->local_node)
+		return -ENOLINK;

 	fwnode = fwnode_graph_get_remote_endpoint(fwnode);
-	if (!fwnode) {
-		fwnode_handle_put(fwnode);
-		return -ENOLINK;
-	}
+	if (!fwnode)
+		goto err_put_local_node;

 	fwnode_graph_parse_endpoint(fwnode, &fwep);
 	link->remote_id = fwep.id;
 	link->remote_port = fwep.port;
 	link->remote_node = fwnode_graph_get_port_parent(fwnode);
+	if (!link->remote_node)
+		goto err_put_local_node;

 	return 0;
+
+err_put_local_node:
+	fwnode_handle_put(link->local_node);
+	return -ENOLINK;
 }
 EXPORT_SYMBOL_GPL(v4l2_fwnode_parse_link);


CJ