Re: [Xen-devel] [PATCH 2/4] xen/hvc: Fix error cases aroundHVM_PARAM_CONSOLE_PFN

From: Stefano Stabellini
Date: Thu May 24 2012 - 06:47:47 EST


On Wed, 23 May 2012, Konrad Rzeszutek Wilk wrote:
> We weren't resetting the parameter to be passed in to a
> known default. Nor were we checking the return value of
> hvm_get_parameter.
>
> CC: stable@xxxxxxxxxx
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>
> drivers/tty/hvc/hvc_xen.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
> index afc7fc2..3277f0e 100644
> --- a/drivers/tty/hvc/hvc_xen.c
> +++ b/drivers/tty/hvc/hvc_xen.c
> @@ -219,7 +219,8 @@ static int xen_hvm_console_init(void)
> if (r < 0)
> goto err;
> info->evtchn = v;
> - hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
> + v = 0;
> + r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
> if (r < 0)
> goto err;
> mfn = v;

Is 0 the right default here?
Maybe something invalid like (~0UL) would be better?
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