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

Rob Herring
2017-03-22T14:40:27Z

On Tue, Mar 21, 2017 at 9:25 PM, Jeffy Chen <jeffy.chen@rock-chips.com> 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@rock-chips.com>
> ---
>
> 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.

If we have a leak, can't you just add a free in the correct spot? That
would be a lot easier to review.

Rob