Messages in this thread | | | Date | Fri, 17 Jun 2022 07:01:27 +0200 | Subject | Re: [PATCH] powerpc: powernv: Fix refcount leak bug in opal-powercap | From | Christophe JAILLET <> |
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Le 17/06/2022 à 06:20, Liang He a écrit : > In opal_powercap_init(), of_find_compatible_node() will return > a node pointer with refcount incremented. We should use of_node_put() > in fail path or when it is not used anymore. > > Besides, for_each_child_of_node() will automatically *inc* and *dec* > refcount during iteration. However, we should add the of_node_put() > if there is a break.
Hi,
I'm not sure that your patch is right here. Because of this *inc* and *dec* things, do we still need to of_node_put(powercap) once we have entered for_each_child_of_node?
I think that this reference will be released on the first iteration of the loop.
Maybe of_node_put(powercap) should be duplicated everywhere it is relevant and removed from the error handling path? Or an additional reference should be taken before the loop? Or adding a new label with "powercap = NULL" and branching there when needed?
CJ
> > Signed-off-by: Liang He <windhl@126.com> > --- > arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c > index 64506b46e77b..b102477d3f95 100644 > --- a/arch/powerpc/platforms/powernv/opal-powercap.c > +++ b/arch/powerpc/platforms/powernv/opal-powercap.c > @@ -153,7 +153,7 @@ void __init opal_powercap_init(void) > pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps), > GFP_KERNEL); > if (!pcaps) > - return; > + goto out_powercap; > > powercap_kobj = kobject_create_and_add("powercap", opal_kobj); > if (!powercap_kobj) { > @@ -236,6 +236,9 @@ void __init opal_powercap_init(void) > kfree(pcaps[i].pg.name); > } > kobject_put(powercap_kobj); > + of_node_put(node); > out_pcaps: > kfree(pcaps); > +out_powercap: > + of_node_put(powercap); > }
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