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Date: Wed, 17 May 2017 16:08:41 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Jeffy Chen <jeffy.chen@...k-chips.com>
Cc: linux-pci@...r.kernel.org, robh@...nel.org, toshi.kani@....com,
shawn.lin@...k-chips.com, briannorris@...omium.org,
linux-kernel@...r.kernel.org, dianders@...omium.org,
bhelgaas@...gle.com, dtor@...omium.org, devicetree@...r.kernel.org,
Rob Herring <robh+dt@...nel.org>,
Frank Rowand <frowand.list@...il.com>
Subject: Re: [PATCH v5] of/pci: Fix memory leak in
of_pci_get_host_bridge_resources
On Wed, Apr 05, 2017 at 10:28:22AM +0800, Jeffy Chen wrote:
> Currently we only free the allocated resource struct when error.
> This would cause memory leak after pci_free_resource_list.
I think I see the problem here. The release path is this:
pci_release_host_bridge_dev
pci_free_resource_list
resource_list_free
list_for_each_entry_safe(entry, tmp, head, node)
resource_list_destroy_entry
resource_list_del
resource_list_free_entry
kfree(entry)
but that frees only the struct resource_entry, not the struct resource
pointed to by entry->res. Is that right?
And this patch solves it for of_pci_get_host_bridge_resources() by
always making entry->res point to entry->__res, which is an element in
struct resource_entry, so it's sufficient to free the resource_entry.
The memory management here is pretty tangled. I wonder if there's
some way to simplify it so it's easier to make sure everybody does it
correctly. For example, could we remove the entry->res pointer
completely and force everybody to use entry->__res?
> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
> ---
>
> Changes in v5:
> Fix some careless compile errors.
>
> Changes in v4:
> Use IORESOURCE_AUTO to mark struct resources which could be copied.
>
> Changes in v3:
> Add some comments.
>
> Changes in v2:
> Don't change the resource_list_create_entry's behavior.
>
> drivers/of/of_pci.c | 51 ++++++++++++++++++---------------------------------
> drivers/pci/bus.c | 7 ++++++-
> 2 files changed, 24 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index 0ee42c3..49233bf 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 +198,21 @@ 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);
> +
> + res.flags |= IORESOURCE_AUTO;
> + pci_add_resource(resources, &res);
>
> /* Check for ranges property */
> err = of_pci_range_parser_init(&parser, dev);
> @@ -244,24 +239,16 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
> if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
> continue;
>
> - res = kzalloc(sizeof(struct resource), GFP_KERNEL);
> - if (!res) {
> - err = -ENOMEM;
> - goto parse_failed;
> - }
> -
> - err = of_pci_range_to_resource(&range, dev, res);
> - if (err) {
> - kfree(res);
> + err = of_pci_range_to_resource(&range, dev, &res);
> + if (err)
> continue;
> - }
>
> - if (resource_type(res) == IORESOURCE_IO) {
> + if (resource_type(&res) == IORESOURCE_IO) {
> if (!io_base) {
> pr_err("I/O range found for %s. Please provide an io_base pointer to save CPU base address\n",
> dev->full_name);
> err = -EINVAL;
> - goto conversion_failed;
> + goto parse_failed;
> }
> if (*io_base != (resource_size_t)OF_BAD_ADDR)
> pr_warn("More than one I/O resource converted for %s. CPU base address for old range lost!\n",
> @@ -269,16 +256,14 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
> *io_base = range.cpu_addr;
> }
>
> - pci_add_resource_offset(resources, res, res->start - range.pci_addr);
> + res.flags |= IORESOURCE_AUTO;
> + pci_add_resource_offset(resources, &res,
> + res.start - range.pci_addr);
> }
>
> return 0;
>
> -conversion_failed:
> - kfree(res);
> parse_failed:
> - resource_list_for_each_entry(window, resources)
> - kfree(window->res);
> pci_free_resource_list(resources);
> return err;
> }
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index bc56cf1..3dbcb95 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -22,12 +22,17 @@ void pci_add_resource_offset(struct list_head *resources, struct resource *res,
> {
> struct resource_entry *entry;
>
> - entry = resource_list_create_entry(res, 0);
> + entry = resource_list_create_entry(NULL, 0);
If we make this change, there are no callers of
resource_list_create_entry() that supply a non-NULL "res", so
we could remove that argument completely.
> if (!entry) {
> printk(KERN_ERR "PCI: can't add host bridge window %pR\n", res);
> return;
> }
>
> + if (res->flags & IORESOURCE_AUTO)
> + *entry->res = *res;
> + else
> + entry->res = res;
> +
> entry->offset = offset;
> resource_list_add_tail(entry, resources);
> }
> --
> 2.1.4
>
>
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