linux-kernel - Re: [PATCH 4.9 10/30] mips/pic32/pic32mzda: Fix refcount leak bugs

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Message-ID: <YzHOgvFqsn6wu2eO@kroah.com>
Date:   Mon, 26 Sep 2022 18:08:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Pavel Machek <pavel@...x.de>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Liang He <windhl@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.9 10/30] mips/pic32/pic32mzda: Fix refcount leak bugs

On Mon, Sep 26, 2022 at 12:40:42PM +0200, Pavel Machek wrote:
> Hi!
> 
> > [ Upstream commit eb9e9bc4fa5fb489c92ec588b3fb35f042ba6d86 ]
> > 
> > of_find_matching_node(), of_find_compatible_node() and
> > of_find_node_by_path() will return node pointers with refcout
> > incremented. We should call of_node_put() when they are not
> > used anymore.
> 
> True. But we absolutely should not call put when we still use the
> reference.
> 
> > +++ b/arch/mips/pic32/pic32mzda/init.c
> > @@ -131,13 +131,18 @@ static int __init pic32_of_prepare_platform_data(struct of_dev_auxdata *lookup)
> >  		np = of_find_compatible_node(NULL, NULL, lookup->compatible);
> >  		if (np) {
> >  			lookup->name = (char *)np->name;
> > -			if (lookup->phys_addr)
> > +			if (lookup->phys_addr) {
> > +				of_node_put(np);
> >  				continue;
> > +			}
> >  			if (!of_address_to_resource(np, 0, &res))
> >  				lookup->phys_addr = res.start;
> > +			of_node_put(np);
> >  		}
> >  	}
> 
> As we stored np->name in lookup, we should not be putting that node,
> we are still using it.

Now dropped, thanks.

greg k-h