Re: [PATCH v5] of/pci: Fix memory leak in of_pci_get_host_bridge_resources
From: jeffy
Date: Thu May 18 2017 - 01:27:35 EST
Hi Bjorn,
On 05/18/2017 05:08 AM, Bjorn Helgaas wrote:
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?
right, that's the leak.
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?
i've tried something like this in
https://patchwork.kernel.org/patch/9638003/
but it turns out there are a few codes trying to use shared
resources(entry->res pointer point to some common resources), for example:
./arch/tile/kernel/pci.c:307:
pci_add_resource(&resources, &ioport_resource);
./arch/tile/kernel/pci.c:308:
pci_add_resource(&resources, &iomem_resource);
so i tried to use IORESOURCE_AUTO to handle non-common(private) resources.
and i saw drivers/pnp/manager.c tried to handle something like this too,
by manually free resources marked as IORESOURCE_AUTO:
static void pnp_clean_resource_table(struct pnp_dev *dev)
{
struct pnp_resource *pnp_res, *tmp;
list_for_each_entry_safe(pnp_res, tmp, &dev->resources, list) {
if (pnp_res->res.flags & IORESOURCE_AUTO)
pnp_free_resource(pnp_res);
}
}
Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
---
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