PNPACPI: ignore _PRS interrupt numbers larger than PNP_IRQ_NR

ACPI Extended Interrupt Descriptors can encode 32-bit interrupt
numbers, so an interrupt number may exceed the size of the bitmap
we use to track possible IRQ settings.

To avoid corrupting memory, complain and ignore too-large interrupt
numbers.

There's similar code in pnpacpi_parse_irq_option(), but I didn't
change that because the small IRQ descriptor can only encode
IRQs 0-15, which do not exceed bitmap size.

In the future, we could handle IRQ numbers greater than PNP_IRQ_NR
by replacing the bitmap with a table or list.
Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NRene Herman <rene.herman@gmail.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/pnp/pnpacpi/rsparser.c

@@ -455,9 +455,16 @@ static __init void pnpacpi_parse_ext_irq_option(struct pnp_dev *dev,
 		return;
 
 	bitmap_zero(map.bits, PNP_IRQ_NR);
-	for (i = 0; i < p->interrupt_count; i++)
-		if (p->interrupts[i])
+	for (i = 0; i < p->interrupt_count; i++) {
+		if (p->interrupts[i]) {
+			if (p->interrupts[i] < PNP_IRQ_NR)
 				__set_bit(p->interrupts[i], map.bits);
+			else
+				dev_err(&dev->dev, "ignoring IRQ %d option "
+					"(too large for %d entry bitmap)\n",
+					p->interrupts[i], PNP_IRQ_NR);
+		}
+	}
 
 	flags = irq_flags(p->triggering, p->polarity, p->sharable);
 	pnp_register_irq_resource(dev, option, &map, flags);