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Re: [Qemu-ppc] [PATCH] spapr_vty: lookup should only return valid VTY ob
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCH] spapr_vty: lookup should only return valid VTY objects |
Date: |
Wed, 1 Jul 2015 15:23:17 +1000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
Ugh, sorry, this version is buggy, I'll resend.
On Wed, Jul 01, 2015 at 01:51:43PM +1000, David Gibson wrote:
> From: Greg Kurz <address@hidden>
>
> If a guest passes the reg property of a valid VIO object that is not a VTY
> to either H_GET_TERM_CHAR or H_PUT_TERM_CHAR, QEMU hits a dynamic cast
> assertion and aborts.
>
> PAPR+ says "Hypervisor checks the termno parameter for validity against the
> Vterm IOA unit addresses assigned to the partition, else return H_Parameter."
>
> This patch adds a type check to ensure vty_lookup() either returns a pointer
> to a valid VTY object or NULL. H_GET_TERM_CHAR and H_PUT_TERM_CHAR will
> now return H_PARAMETER to the guest instead of crashing.
>
> The patch has no effect on the reg == 0 hack used to implement the RTAS call
> display-character.
>
> Signed-off-by: Greg Kurz <address@hidden>
> Signed-off-by: David Gibson <address@hidden>
> ---
> hw/char/spapr_vty.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> I've already merged this into spapr-next and it will be in the next
> batch I send if not merged before that.
>
> But I think this is an important enough fix (it allows the guest to
> crash qemu) that it should probably be fastracked into mainline and
> stable.
>
> diff --git a/hw/char/spapr_vty.c b/hw/char/spapr_vty.c
> index 1d53035..f407cd0 100644
> --- a/hw/char/spapr_vty.c
> +++ b/hw/char/spapr_vty.c
> @@ -228,7 +228,7 @@ VIOsPAPRDevice *vty_lookup(sPAPRMachineState *spapr,
> target_ulong reg)
> return spapr_vty_get_default(spapr->vio_bus);
> }
>
> - return sdev;
> + return object_dynamic_cast(sdev, TYPE_VIO_SPAPR_VTY_DEVICE);
> }
>
> static void spapr_vty_register_types(void)
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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