[PATCH] ACPI: bounds check IRQ to prevent memory corruption

Bjorn Helgaas
2008-08-01T21:58:34Z

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>
---

drivers/acpi/pci_link.c | 12 +++++++-----
1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
index 89f3b2a..cf47805 100644
--- a/drivers/acpi/pci_link.c
+++ b/drivers/acpi/pci_link.c
@@ -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)
@@ -872,10 +872,12 @@ static int __init acpi_irq_penalty_update(char *str, int used)
*/
void acpi_penalize_isa_irq(int irq, int active)
{
- if (active)
- acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_USED;
- else
- acpi_irq_penalty[irq] += PIRQ_PENALTY_PCI_USING;
+ 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;
+ }
}

/*