drm/i915: Prevent writing into a read-only object via a GGTT mmap
commit 3e977ac6179b39faa3c0eda5fce4f00663ae298d upstream.
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.
v3: Remove VM_MAYWRITE to curtail mprotect()
Testcase: igt/gem_userptr_blits/readonly_mmap*
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Cc: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com> #v1
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180712185315.3288-4-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/drm/drm_vma_manager.h b/include/drm/drm_vma_manager.h
index 9c03895..72bf408 100644
--- a/include/drm/drm_vma_manager.h
+++ b/include/drm/drm_vma_manager.h
@@ -42,6 +42,7 @@
rwlock_t vm_lock;
struct drm_mm_node vm_node;
struct rb_root vm_files;
+ bool readonly:1;
};
struct drm_vma_offset_manager {