On Tue, Oct 13, 2026 at 01:54:32PM +0100, Akash Goel wrote:
> The BOs created with DRM_PANTHOR_BO_NO_MMAP flag are not supposed to be
> mmappable by the Userspace. But after the rework to support shrinker,
> it became possible to mmap NO_MMAP BOs. Userspace could second guess
> the file offset range, allocated unconditionally at the BO creation
> time, and create a CPU mapping. There may not be any adverse effect of
> such a CPU mapping though.
> This commit adds a check in the mmap callback of Panthor driver to
> fail the mmap() attempts on BOs created with NO_MMAP flag. The check
> covers private BOs as well as the prime exported BOs that are mmapped
> using prime fd.
>
> v2:
> - Fix breakage of mmap() on exported BOs that didn't have
> BO_MMAP_OFFSET ioctl invoked for them.
>
> Fixes: 68cbf96b1e9b ("drm/panthor: Part ways with drm_gem_shmem_object")
> Suggested-by: Boris Brezillon <[email protected]>
> Signed-off-by: Akash Goel <[email protected]>
Reviewed-by: Liviu Dudau <[email protected]>
Best regards,
Liviu
> ---
> drivers/gpu/drm/panthor/panthor_gem.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c
> b/drivers/gpu/drm/panthor/panthor_gem.c
> index c07a44057e42..22b57ab6f929 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -744,6 +744,9 @@ static int panthor_gem_mmap(struct drm_gem_object *obj,
> struct vm_area_struct *v
> struct panthor_gem_object *bo = to_panthor_bo(obj);
> int ret;
>
> + if (bo->flags & DRM_PANTHOR_BO_NO_MMAP)
> + return -EINVAL;
> +
> if (drm_gem_is_imported(obj)) {
> /* Reset both vm_ops and vm_private_data, so we don't end up
> with
> * vm_ops pointing to our implementation if the dma-buf backend
> --
> 2.25.1
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
