Re: [PATCH] powerpc: kernel: fix a refcount leak in format_show()

[Hangyu Hua]

Thanks. I will resubmit my patch latter.

On 2022/3/2 03:50, Tyrel Datwyler wrote:
> On 3/1/22 04:55, Michael Ellerman wrote:
> > Hangyu Hua <hbh25y@xxxxxxxxx> writes:
> > > node needs to be dropped when of_property_read_string fails. So an earlier call
> > > to of_node_put is required here.
> >
> > That's true but ...
> >
> > > diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
> > > index a0a78aba2083..cd0fa7028d86 100644
> > > --- a/arch/powerpc/kernel/secvar-sysfs.c
> > > +++ b/arch/powerpc/kernel/secvar-sysfs.c
> > > @@ -30,13 +30,12 @@ static ssize_t format_show(struct kobject *kobj, struct kobj_attribute *attr,
> > >   		return -ENODEV;
> >
> > There's also a reference leak there ^
> >
> > So if you're going to touch this code I'd like you to fix both reference
> > leaks in a single patch please.
> >
> > Having the error cases set rc and then goto "out" which does the
> > of_node_put() is the obvious solution I think.
>
> update_kobj_size() in the same source file provides a good example of the
> suggested solution.
>
> -Tyrel
>
> > cheers
> >
> > >   	rc = of_property_read_string(node, "format", &format);
> > > +	of_node_put(node);
> > >   	if (rc)
> > >   		return rc;
> > >   
> > >   	rc = sprintf(buf, "%s\n", format);
> > >   
> > > -	of_node_put(node);
> > > -
> > >   	return rc;
> > >   }
> > >   
> > > --
> > > 2.25.1