Messages in this thread | | | Subject | Re: [PATCH 3/3] spi: spi-axi: take extra controller reference before deregistration | From | Lars-Peter Clausen <> | Date | Mon, 30 Oct 2017 10:48:23 +0100 |
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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.
> > 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 <lars@metafoo.de> > Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Thanks.
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