[PATCH 4.4 52/53] ACPI: ioapic: Clear on-stack resource before using it

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joerg Roedel <jroedel@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 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) == 0)
 		return AE_OK;