[PATCH 03/22] drm/tegra: Check whether page belongs to BO in tegra_bo_kmap()

[Mikko Perttunen]

On 05/23/2017 03:14 AM, Dmitry Osipenko wrote:
> This fixes an OOPS in case of out-of-bounds accessing of a kmap'ed cmdbuf
> (non-IOMMU allocation) while patching the relocations in do_relocs().
> 
> Signed-off-by: Dmitry Osipenko <digetx at gmail.com>
> ---
>   drivers/gpu/drm/tegra/gem.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
> index 424569b53e57..ca0d4439e97b 100644
> --- a/drivers/gpu/drm/tegra/gem.c
> +++ b/drivers/gpu/drm/tegra/gem.c
> @@ -74,6 +74,9 @@ static void *tegra_bo_kmap(struct host1x_bo *bo, unsigned int page)
>   {
>   	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
>   
> +	if (page * PAGE_SIZE >= obj->gem.size)
> +		return NULL;
> +

The multiplication here could overflow, so it needs the same u64 
treatment to catch all problem situations. I'm not sure if this is 
required, though, with the other bounds check patches in this series.

>   	if (obj->vaddr)
>   		return obj->vaddr + page * PAGE_SIZE;
>   	else if (obj->gem.import_attach)
>