Re: [PATCH] kernel/irq/irqdomain.c: fix memory leak with using debugfs_lookup()

[Marc Zyngier]

On Thu, 02 Feb 2023 16:51:50 +0000,
Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> 
> On Thu, Feb 02, 2023 at 04:48:30PM +0000, Marc Zyngier wrote:
> > On Thu, 02 Feb 2023 15:15:54 +0000,
> > Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > > 
> > > When calling debugfs_lookup() the result must have dput() called on it,
> > > otherwise the memory will leak over time.  To make things simpler, just
> > > call debugfs_lookup_and_remove() instead which handles all of the logic
> > > at once.
> > > 
> > > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > ---
> > >  kernel/irq/irqdomain.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > > index 8fe1da9614ee..e2096b51c004 100644
> > > --- a/kernel/irq/irqdomain.c
> > > +++ b/kernel/irq/irqdomain.c
> > > @@ -1915,7 +1915,7 @@ static void debugfs_add_domain_dir(struct irq_domain *d)
> > >  
> > >  static void debugfs_remove_domain_dir(struct irq_domain *d)
> > >  {
> > > -	debugfs_remove(debugfs_lookup(d->name, domain_dir));
> > > +	debugfs_lookup_and_remove(d->name, domain_dir);
> > >  }
> > >  
> > >  void __init irq_domain_debugfs_init(struct dentry *root)
> > 
> > Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>
> > 
> > Maybe add a Cc stable to get this in 6.1?
> 
> Sure, I can, but how often are irq domains removed from the system under
> a normal operation?

As many time as you want if you're doing virtualisation and have the
right sort of HW (anything GICv4.x, for example, which will create
per-VM irqdomains).

> Or you can take it through your tree and add that?  I too can take
> it through mine, which ever is easier for you.

Sure, I can queue that, although that will probably be next week.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.