Commit fa46d352 authored Aug 01, 2008 by Bjorn Helgaas Committed by Andi Kleen Aug 15, 2008

ACPI: bounds check IRQ to prevent memory corruption



acpi_penalize_isa_irq() should validate irq before using it to
index the acpi_irq_penalty[] table.

Here's the path I'm concerned about:

    pnpacpi_parse_allocated_irqresource()
    {
	...
	irq = acpi_register_gsi(gsi, triggering, polarity);
	if (irq >= 0)
		pcibios_penalize_isa_irq(irq, 1);

There's no guarantee that acpi_register_gsi() will return an IRQ
within the bounds of acpi_irq_penalty[].

I have not seen a failure I can attribute to this.  However,
ACPI_MAX_IRQS is only 256, and I'm pretty sure ia64 can have
IRQs larger than that.

I think this should go in 2.6.27.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

parent b635acec

drivers/acpi/pci_link.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -849,7 +849,7 @@ static int __init acpi_irq_penalty_update(char *str, int used)
		if (irq < 0)
		continue;

		if (irq >= ACPI_MAX_IRQS)
		if (irq >= ARRAY_SIZE(acpi_irq_penalty))
		continue;

		if (used)
		@@ -872,11 +872,13 @@ static int __init acpi_irq_penalty_update(char *str, int used)
		*/
		void acpi_penalize_isa_irq(int irq, int active)
		{
		if (irq >= 0 && irq < ARRAY_SIZE(acpi_irq_penalty)) {
		if (active)
		acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_USED;
		else
		acpi_irq_penalty[irq] += PIRQ_PENALTY_PCI_USING;
		}
		}

		/*
		* Over-ride default table to reserve additional IRQs for use by ISA