Re: [PATCH] drivers/base/node: Fix double free in register_one_node()

[Donet Tom]

On 9/18/25 11:25 AM, David Hildenbrand wrote:
> On 18.09.25 07:41, Donet Tom wrote:
> > When device_register() fails in register_node(), it calls
> > put_device(&node->dev). This triggers node_device_release(),
> > which calls kfree(to_node(dev)), thereby freeing the entire
> > node structure.
> >
> > As a result, when register_node() returns an error, the node
> > memory has already been freed. Calling kfree(node) again in
> > register_one_node() leads to a double free.
> >
> > This patch removes the redundant kfree(node) from
> > register_one_node() to prevent the double free.
> >
> > Fixes: 786eb990cfb7 ("drivers/base/node: handle error properly in 
> > register_one_node()")
> > Signed-off-by: Donet Tom <donettom@xxxxxxxxxxxxx>
> > ---
> >   drivers/base/node.c | 1 -
> >   1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/base/node.c b/drivers/base/node.c
> > index 1608816de67f..6b6e55a98b79 100644
> > --- a/drivers/base/node.c
> > +++ b/drivers/base/node.c
> > @@ -885,7 +885,6 @@ int register_one_node(int nid)
> >       error = register_node(node_devices[nid], nid);
> >       if (error) {
> >           node_devices[nid] = NULL;
> > -        kfree(node);
> >           return error;
> >       }
>
> Yes, that matches what other users (staring at mm/memory-tiers.c) do.
>
> I wonder if we should just inline register_node() into 
> register_one_node().
>
> Then it's clearer that we perform a put_device() already in there.
>
> On top of that, we could then just s/register_one_node/register_node/
>
> And then we could do a similar cleanup for unregister_one_node / 
> unregister_node where I don't consider the split function really 
> valuable.


Sure David, I will work on it and send it as a separate patch.