[PATCH 1/7] irqchip/gic-v5: Check get_logical_index() return value in MADT IAFFID parsing

[Lorenzo Pieralisi]

In gic_acpi_parse_iaffid() a given MADT GICC entry might not correspond
to a logical cpu recognized by the kernel, resulting in the cpu variable
initialization to an error value.

Currently, the get_logical_index() return value is not checked for failure,
which might result in out-of-bounds memory corruption while trying to
index a per_cpu variable array.

Add a check to evaluate get_logical_index() return value.

Fixes: 35866efa52fe ("irqchip/gic-v5: Add ACPI IRS probing")
Signed-off-by: Lorenzo Pieralisi <lpieralisi at kernel.org>
Cc: Thomas Gleixner <tglx at kernel.org>
Cc: Marc Zyngier <maz at kernel.org>
Link: https://sashiko.dev/#/message/20260810104747.E5CE71F000E9%40smtp.kernel.org
---
 drivers/irqchip/irq-gic-v5-irs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v5-irs.c b/drivers/irqchip/irq-gic-v5-irs.c
index 3028a8bbbf68..0bd9ae9ae12e 100644
--- a/drivers/irqchip/irq-gic-v5-irs.c
+++ b/drivers/irqchip/irq-gic-v5-irs.c
@@ -874,6 +874,8 @@ static int __init gic_acpi_parse_iaffid(union acpi_subtable_headers *header,
 		return 0;
 
 	cpu = get_logical_index(gicc->arm_mpidr);
+	if (cpu < 0)
+		return 0;
 
 	if (gicc->iaffid & ~GENMASK(current_iaffid_bits - 1, 0)) {
 		pr_warn("CPU %d iaffid 0x%x exceeds IRS iaffid bits\n", cpu, gicc->iaffid);

-- 
2.53.0