Quoting Chris Wilson (2018-06-14 22:24:02)
> If the user has created a read-only object, they should not be allowed
> to circumvent the write protection by using a GGTT mmapping. Deny it.
>
> Also most machines do not support read-only GGTT PTEs, so again we have
> to reject attempted writes. Fortunately, this is known a priori, so we
> can at least reject in the call to create the mmap (with a sanity check
> in the fault handler).
>
> v2: Check the vma->vm_flags during mmap() to allow readonly access.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Jon Bloomfield <jon.bloomfield@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Matthew Auld <matthew.william.auld@xxxxxxxxx>
> Cc: David Herrmann <dh.herrmann@xxxxxxxxx>
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> #v1
> Reviewed-by: Matthew Auld <matthew.william.auld@xxxxxxxxx> #v1
> Reviewed-by: Jon Bloomfield <jon.bloomfield@xxxxxxxxx>
<SNIP>
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -1036,6 +1036,11 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
> return -EACCES;
> }
>
> + if (vma->vm_flags & VM_WRITE && node->readonly) {
> + drm_gem_object_put_unlocked(obj);
> + return -EINVAL;
> + }
> +
Pretty sure you want to split this patch and Cc: dri-devel. With that,
both are:
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Regards, Joonas
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