Re: [Qemu-block] [PATCH for-3.1] fdc: fix segfault in fdctrl_stop_transfer() when DMA is disabled

[Hervé Poussineau]

Le 11/11/2018 à 10:40, Mark Cave-Ayland a écrit :
> Commit c8a35f1cf0f "fdc: use IsaDma interface instead of global DMA_*
> functions" accidentally introduced a segfault in fdctrl_stop_transfer() for
> non-DMA transfers.
>
> If fdctrl->dma_chann has not been configured then the fdctrl->dma interface
> reference isn't initialised during isabus_fdc_realize(). Unfortunately
> fdctrl_stop_transfer() unconditionally references the DMA interface when
> finishing the transfer causing a NULL pointer dereference.
>
> Fix the issue by adding a check in fdctrl_stop_transfer() so that the DMA
> interface reference and release method is only invoked if fdctrl->dma_chann
> has been set.
>
> (This issue was discovered by Martin testing a recent change in the NetBSD
> installer under qemu-system-sparc)
>
> Reported-by: Martin Husemann <address@hidden>
> Signed-off-by: Mark Cave-Ayland <address@hidden>

Reviewed-by: Hervé Poussineau <address@hidden>