[added to the v4.1 stable tree] ACPI: ioapic: Clear on-stack resource before using it

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From: Joerg Roedel <jroedel@xxxxxxx>

This patch has been added to the v4.1 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit e3d5092b6756b9e0b08f94bbeafcc7afe19f0996 ]

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: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
 drivers/acpi/ioapic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index ccdc8db16bb8..fa2cf2dc4e33 100644
--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -45,6 +45,12 @@ static acpi_status setup_res(struct acpi_resource *acpi_res, void *data)
 	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;
-- 
2.11.0




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