Re: [PATCH 2/2] of/pci: Fix memory leak in of_pci_get_host_bridge_resources

[jeffy]

Hi Rob,

On 03/22/2017 10:55 PM, Rob Herring wrote:
> On Wed, Mar 22, 2017 at 9:39 AM, Rob Herring <robh@xxxxxxxxxx> wrote:
> > On Tue, Mar 21, 2017 at 9:25 PM, Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx> wrote:
> > > Currently we only free the allocated resource struct when error.
> > > This would cause memory leak after pci_free_resource_list.
> > >
> > > Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
> > > ---
> > >
> > >   drivers/of/of_pci.c | 48 +++++++++++++++---------------------------------
> > >   1 file changed, 15 insertions(+), 33 deletions(-)
> > >
> > > diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> > > index 0ee42c3..269393bc 100644
> > > --- a/drivers/of/of_pci.c
> > > +++ b/drivers/of/of_pci.c
> > > @@ -189,9 +189,7 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
> > >                          unsigned char busno, unsigned char bus_max,
> > >                          struct list_head *resources, resource_size_t *io_base)
> > >   {
> > > -       struct resource_entry *window;
> > > -       struct resource *res;
> > > -       struct resource *bus_range;
> > > +       struct resource res;
> > >          struct of_pci_range range;
> > >          struct of_pci_range_parser parser;
> > >          char range_type[4];
> > > @@ -200,24 +198,19 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
> > >          if (io_base)
> > >                  *io_base = (resource_size_t)OF_BAD_ADDR;
> > >
> > > -       bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> > > -       if (!bus_range)
> > > -               return -ENOMEM;
> > > -
> > >          pr_info("host bridge %s ranges:\n", dev->full_name);
> > >
> > > -       err = of_pci_parse_bus_range(dev, bus_range);
> > > +       err = of_pci_parse_bus_range(dev, &res);
> > >          if (err) {
> > > -               bus_range->start = busno;
> > > -               bus_range->end = bus_max;
> > > -               bus_range->flags = IORESOURCE_BUS;
> > > -               pr_info("  No bus range found for %s, using %pR\n",
> > > -                       dev->full_name, bus_range);
> > > +               res.start = busno;
> > > +               res.end = bus_max;
> > > +               res.flags = IORESOURCE_BUS;
> > > +               pr_info("  No bus range found for %s\n", dev->full_name);
> > >          } else {
> > > -               if (bus_range->end > bus_range->start + bus_max)
> > > -                       bus_range->end = bus_range->start + bus_max;
> > > +               if (res.end > res.start + bus_max)
> > > +                       res.end = res.start + bus_max;
> > >          }
> > > -       pci_add_resource(resources, bus_range);
> > > +       pci_add_resource(resources, &res);
> >
> > You are passing a stack variable to pci_add_resource and it doesn't
> > make a copy of it. I assume the resource needs to live after you exit
> > this function.
>
> Ah, found your 1st patch changing the behavior. I'm surprised that
> change works without affecting anyone else.
sorry, i should add a cover-letter first. and you're right, that would 
affect others(for example the ioport_resource/iomem_resource).
> > If we have a leak, can't you just add a free in the correct spot? That
> > would be a lot easier to review.
it seems hard to tell which resources in the list need to be freed after 
all...
> > Rob