Re: [Qemu-arm] [Qemu-devel] [PATCH 7/8] hw/display/bcm2835_fb: Validate config settings

[Richard Henderson]

On 08/14/2018 07:44 AM, Peter Maydell wrote:
> Validate the config settings that the guest tries to set.
> 
> The wiki page documentation is not really accurate here:
> generally rather than failing requests to set bad parameters,
> the hardware will just clip them to something sensible.
> 
> Validate the most important parameters: sizes and
> the viewport offsets. This prevents the framebuffer
> code from trying to read out-of-range memory.
> 
> In the property handling code, we validate the new parameters every
> time we encounter a tag that sets them. This means we validate the
> config multiple times if the request includes multiple config-setting
> tags, but the code would require significant restructuring to do a
> validation only once but still return the clipped settings for
> get-parameter tags and the buffer allocation tag.
> 
> Validation of settings made via the older bcm2835_fb_mbox_push()
> function will be done in the next commit.
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  include/hw/display/bcm2835_fb.h |  8 +++++
>  hw/display/bcm2835_fb.c         | 48 +++++++++++++++++++++++++++--
>  hw/misc/bcm2835_property.c      | 54 ++++++++++++++++-----------------
>  3 files changed, 81 insertions(+), 29 deletions(-)

Reviewed-by: Richard Henderson <address@hidden>


r~