linux-kernel - Re: linux-next: dock_link

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Date:	Sat, 18 Feb 2012 14:26:10 +0100
From:	Holger Macht <holger@...ac.de>
To:	Hillf Danton <dhillf@...il.com>
Cc:	Hugh Dickins <hughd@...gle.com>, Matthew Garrett <mjg@...hat.com>,
	Jeff Garzik <jgarzik@...hat.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: linux-next: dock_link_device is oopsy

On Sa 18. Feb - 21:05:18, Hillf Danton wrote:
> On Sat, Feb 18, 2012 at 7:14 PM, Holger Macht <holger@...ac.de> wrote:
> > So how about that?
> >
> > acpi: Bail out when linking devices and there are no dock stations
> >
> > If dock_station_count is zero, we allocate zero memory and don't check
> > this at future references. So bail out if there are actually no dock
> > stations.
> >
> > Signed-off-by: Holger Macht <holger@...ac.de>
> > ---
> >  drivers/acpi/dock.c |   19 ++++++++++++++-----
> >  1 files changed, 14 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/acpi/dock.c b/drivers/acpi/dock.c
> > index b5e4142..0b3072c 100644
> > --- a/drivers/acpi/dock.c
> > +++ b/drivers/acpi/dock.c
> > @@ -281,11 +281,15 @@ EXPORT_SYMBOL_GPL(is_dock_device);
> >  */
> >  struct device **dock_link_device(acpi_handle handle)
> >  {
> > -       struct device *dev = acpi_get_physical_device(handle);
> > +       struct device *dev;
> >        struct dock_station *dock_station;
> >        int ret, dock = 0;
> >        struct device **devices;
> >
> > +       if (!dock_station_count)
> > +               return NULL;
> > +
> > +       dev = acpi_get_physical_device(handle);
> >        devices = kmalloc(dock_station_count * sizeof(struct device *),
> >                          GFP_KERNEL);
> >
> > @@ -320,12 +324,17 @@ EXPORT_SYMBOL_GPL(dock_link_device);
> >  */
> >  struct device **dock_unlink_device(acpi_handle handle)
> >  {
> > -       struct device *dev = acpi_get_physical_device(handle);
> > +       struct device *dev;
> >        struct dock_station *dock_station;
> >        int dock = 0;
> > -       struct device **devices =
> > -               kmalloc(dock_station_count * sizeof(struct device *),
> > -                       GFP_KERNEL);
> > +       struct device **devices;
> > +
> > +       if (!dock_station_count)
> > +               return NULL;
> > +
> > +       dev = acpi_get_physical_device(handle);
> > +       devices = kmalloc(dock_station_count * sizeof(struct device *),
> > +                         GFP_KERNEL);
> >
> 
> If bail out in this way, another patch looks needed to fix up
> mem leakage :-(

Sorry if I'm a little slow...but where is the leakage? The function
doesn't allocate anything before bailing out in the dock_station_count
check. And the rerun value should be freed by the caller. Please point
me in the right direction.

Thanks,
 Holger
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