Re: [PATCH] of: property: Add missing of_node_get() in parse_interrupt()

[Jean-Jacques Hiblot]

On 28/02/2023 20:07, Saravana Kannan wrote:
> On Tue, Feb 28, 2023 at 9:40 AM Jean-Jacques Hiblot
> <jjhiblot@xxxxxxxxxxxxxxx> wrote:
> > From: Jean Jacques Hiblot <jjhiblot@xxxxxxxxxxxxxxx>
> >
> > As all the other parsers do, parse_interrupt() must increase the refcount
> > of the device_node. Otherwise the refcount is decremented every time
> > parse_interrupt() is called on this node, leading to a potential
> > use-after-free.
> >
> > This is a regression introduced by commit f265f06af194 ("of: property:
> > Fix fw_devlink handling of interrupts/interrupts-extended"). The reason is
> > that of_irq_parse_one() does not increase the refcount while the previously
> > used of_irq_find_parent() does.
> Thanks for catching the issue Jean!
>
> This feels like a bug in of_irq_parse_one() to me. It's returning a
> reference to a node without doing a of_node_get() on it.
>
> Rob, Marc, Do you agree?

Sarvana,

it looks like you're right. The bug seems to be in of_irq_parse_one().

It doesn't behave in the same way for "interrupts-extended" where it 
does a get() and 'interrupts" where it doesn't.

So please ignore this patch.

Thanks

> Jean,
>
> If they agree, can you please fix of_irq_parse_one() and add a
> of_node_put() to existing callers (if they aren't already doing a
> put()).
>
> Thanks,
> Saravana
>
> > Fixes: f265f06af194 ("of: property: Fix fw_devlink handling of interrupts/interrupts-extended")
> > Signed-off-by: Jean Jacques Hiblot <jjhiblot@xxxxxxxxxxxxxxx>
> > ---
> >   drivers/of/property.c | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/of/property.c b/drivers/of/property.c
> > index 134cfc980b70b..1f23bcb765c4e 100644
> > --- a/drivers/of/property.c
> > +++ b/drivers/of/property.c
> > @@ -1380,7 +1380,10 @@ static struct device_node *parse_interrupts(struct device_node *np,
> >              strcmp(prop_name, "interrupts-extended"))
> >                  return NULL;
> >
> > -       return of_irq_parse_one(np, index, &sup_args) ? NULL : sup_args.np;
> > +       if (of_irq_parse_one(np, index, &sup_args))
> > +               return NULL;
> > +
> > +       return of_node_get(sup_args.np);
> >   }
> >
> >   static const struct supplier_bindings of_supplier_bindings[] = {
> > --
> > 2.25.1