On Mon, Oct 30, 2017 at 10:48:23AM +0100, Lars-Peter Clausen wrote: > On 10/29/2017 12:56 PM, Johan Hovold wrote: > > Take an extra reference to the controller to avoid use-after-free in > > free_irq() which is called only after the controller has been > > deregistered and freed. > > > > Note that this is not an issue for this particular driver which does not > > use shared interrupts, but free_irq() could otherwise end up accessing > > the freed controller when CONFIG_DEBUG_SHIRQ is set. > > Strictly speaking there is no guarantee that the IRQ handler does not run > until free_irq() has been called. And since the SPI master is referenced in > the IRQ handler there could be an use-after-free condition. So there is kind > of a real issue here as well. But it should be really really hard to trigger > it unless the hardware misbehaves.
You're right of course. Let me update the commit message in a v2 of the series. > > Defer controller release until free_irq() returns to prevent this > > from ever becoming an issue should this code be replicated in other > > drivers. > > > > Cc: Lars-Peter Clausen <l...@metafoo.de> > > Signed-off-by: Johan Hovold <jo...@kernel.org> > > Acked-by: Lars-Peter Clausen <l...@metafoo.de> Thanks, Johan
