Re: [PATCH 6/9] drm/vc4: Annotate struct vc4_perfmon with __counted_by

[Gustavo A. R. Silva]

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 vc4_perfmon.

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

Cc: Emma Anholt 
Cc: Maxime Ripard 
Cc: David Airlie 
Cc: Daniel Vetter 
Cc: dri-de...@lists.freedesktop.org
Signed-off-by: Kees Cook 


Reviewed-by: Gustavo A. R. Silva 

Thanks
--
Gustavo


---
  drivers/gpu/drm/vc4/vc4_drv.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index bf66499765fb..ab61e96e7e14 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -76,7 +76,7 @@ struct vc4_perfmon {
 * Note that counter values can't be reset, but you can fake a reset by
 * destroying the perfmon and creating a new one.
 */
-   u64 counters[];
+   u64 counters[] __counted_by(ncounters);
  };
  
  struct vc4_dev {

[PATCH 6/9] drm/vc4: Annotate struct vc4_perfmon with __counted_by

[Kees Cook]

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 vc4_perfmon.

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

Cc: Emma Anholt 
Cc: Maxime Ripard 
Cc: David Airlie 
Cc: Daniel Vetter 
Cc: dri-de...@lists.freedesktop.org
Signed-off-by: Kees Cook 
---
 drivers/gpu/drm/vc4/vc4_drv.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index bf66499765fb..ab61e96e7e14 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -76,7 +76,7 @@ struct vc4_perfmon {
 * Note that counter values can't be reset, but you can fake a reset by
 * destroying the perfmon and creating a new one.
 */
-   u64 counters[];
+   u64 counters[] __counted_by(ncounters);
 };
 
 struct vc4_dev {
-- 
2.34.1