Re: [PATCH] pci: assert that irqnum is between 0 and bus->nirqs in pci_change_irq_level()

[Mark Cave-Ayland]

On 11/10/2020 09:20, Mark Cave-Ayland wrote:

> These assertions similar to those in the adjacent pci_bus_get_irq_level() 
> function
> ensure that irqnum lies within the valid PCI bus IRQ range.
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> ---
> 
> This would have immediately picked up on the sabre PCI bus IRQ overflow fixed 
> by
> the patch I just posted.
> 
> ---
>  hw/pci/pci.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 3c8f10b461..b1484b3747 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -258,6 +258,8 @@ static void pci_change_irq_level(PCIDevice *pci_dev, int 
> irq_num, int change)
>              break;
>          pci_dev = bus->parent_dev;
>      }
> +    assert(irq_num >= 0);
> +    assert(irq_num < bus->nirq);
>      bus->irq_count[irq_num] += change;
>      bus->set_irq(bus->irq_opaque, irq_num, bus->irq_count[irq_num] != 0);
>  }

Actually something else is odd here: I've just done a quick check on the 
callers to
pci_change_irq_level() and it appears that both pci_update_irq_disabled() and
pci_irq_handler() assume that irqnum is a PCI device IRQ i.e between 0 and 3, 
whereas
pci_change_irq_level() assumes it is working with a PCI bus IRQ between 0 and 
bus->nirqs.

It feels like pci_change_irq_level() should be renamed to 
pci_bus_change_irq_level()
similar to pci_bus_get_irq_level() but in that case are 
pci_update_irq_disabled() and
pci_irq_handler() both incorrect?


ATB,

Mark.