[7/9] drm/virtio: Annotate struct virtio_gpu_object_array with __counted_by

Commit Message

Kees Cook Sept. 22, 2023, 5:32 p.m. UTC

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct virtio_gpu_object_array.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: David Airlie <[e-mail]>
Cc: Gerd Hoffmann <[e-mail]>
Cc: Gurchetan Singh <[e-mail]>
Cc: Chia-I Wu <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Kees Cook <[e-mail]>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Gustavo A. R. Silva Sept. 23, 2023, 2:36 a.m. UTC | #1

On 9/22/23 11:32, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct virtio_gpu_object_array.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: David Airlie <[e-mail]>
> Cc: Gerd Hoffmann <[e-mail]>
> Cc: Gurchetan Singh <[e-mail]>
> Cc: Chia-I Wu <[e-mail]>
> Cc: Daniel Vetter <[e-mail]>
> Cc: [e-mail]
> Cc: [e-mail]
> Signed-off-by: Kees Cook <[e-mail]>

Reviewed-by: Gustavo A. R. Silva <[e-mail]>

Thanks

Patch

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 8513b671f871..96365a772f77 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -119,7 +119,7 @@  struct virtio_gpu_object_array {
 	struct ww_acquire_ctx ticket;
 	struct list_head next;
 	u32 nents, total;
-	struct drm_gem_object *objs[];
+	struct drm_gem_object *objs[] __counted_by(total);
 };
 
 struct virtio_gpu_vbuffer;