[PATCH 6/6] irqchip/loongson-eiointc: validate MADT BIO-PIC entries

[Jiale Yao <yaojiale02@163.com>]

The BIO-PIC MADT callback reads the controller address before checking
that firmware supplied the complete fixed-size record. A truncated entry
can therefore cause an out-of-bounds read while selecting the parent
domain.

Validate the BIO-PIC record before accessing its address or passing it
to the initialization helper.

Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 drivers/irqchip/irq-loongson-eiointc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
index a9e8b481d31d..f92e7702195a 100644
--- a/drivers/irqchip/irq-loongson-eiointc.c
+++ b/drivers/irqchip/irq-loongson-eiointc.c
@@ -454,8 +454,14 @@ static int __init pch_pic_parse_madt(union acpi_subtable_headers *header,
 					const unsigned long end)
 {
 	struct acpi_madt_bio_pic *pchpic_entry = (struct acpi_madt_bio_pic *)header;
-	unsigned int node = (pchpic_entry->address >> 44) & 0xf;
-	struct irq_domain *parent = acpi_get_vec_parent(node, pch_group);
+	struct irq_domain *parent;
+	unsigned int node;
+
+	if (BAD_MADT_ENTRY(pchpic_entry, end))
+		return -EINVAL;
+
+	node = (pchpic_entry->address >> 44) & 0xf;
+	parent = acpi_get_vec_parent(node, pch_group);
 
 	if (parent)
 		return pch_pic_acpi_init(parent, pchpic_entry);
-- 
2.34.1