linux-kernel - Re: [PATCH] media: v4l2-core: Fix a potential resource leak in v4l2_fwnode_parse

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Date:   Tue, 13 Jun 2023 19:15:40 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-media@...r.kernel.org
Subject: Re: [PATCH] media: v4l2-core: Fix a potential resource leak in
 v4l2_fwnode_parse_link()

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@...adoo.fr>
>> ---
>> /!\  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