[PATCH 4.9 81/84] ACPI: ioapic: Clear on-stack resource before using it

Greg Kroah-Hartman
2017-08-28T08:13:31Z

From: Joerg Roedel <jroedel@suse.de>

commit e3d5092b6756b9e0b08f94bbeafcc7afe19f0996 upstream.

The on-stack resource-window 'win' in setup_res() is not
properly initialized. This causes the pointers in the
embedded 'struct resource' to contain stale addresses.

These pointers (in my case the ->child pointer) later get
propagated to the global iomem_resources list, causing a #GP
exception when the list is traversed in
iomem_map_sanity_check().

Fixes: c183619b63ec (x86/irq, ACPI: Implement ACPI driver to support IOAPIC hotplug)
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/acpi/ioapic.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -45,6 +45,12 @@ static acpi_status setup_res(struct acpi
struct resource *res = data;
struct resource_win win;

+ /*
+ * We might assign this to 'res' later, make sure all pointers are
+ * cleared before the resource is added to the global list
+ */
+ memset(&win, 0, sizeof(win));
+
res->flags = 0;
if (acpi_dev_filter_resource_type(acpi_res, IORESOURCE_MEM))
return AE_OK;