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 audit_chunk.

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

Cc: Paul Moore <paul@paul-moore.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: audit@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 kernel/audit_tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index e867c17d3f84..85a5b306733b 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -34,7 +34,7 @@ struct audit_chunk {
 		struct list_head list;
 		struct audit_tree *owner;
 		unsigned index;		/* index; upper bit indicates 'will prune' */
-	} owners[];
+	} owners[] __counted_by(count);
 };
 
 struct audit_tree_mark {
-- 
2.34.1

On Aug 17, 2023 Paul Moore <paul@paul-moore.com> 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 audit_chunk.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Eric Paris <eparis@redhat.com>
> Cc: audit@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  kernel/audit_tree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Merged into audit/next, thanks.

--
paul-moore.com

On Thu, Aug 17, 2023 at 4:35 PM Kees Cook <keescook@chromium.org> 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 audit_chunk.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Eric Paris <eparis@redhat.com>
> Cc: audit@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  kernel/audit_tree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

This looks good to me, but considering we are currently at -rc6 I'd
prefer to hold off until after the upcoming merge window.  I'll send
another note once it's been merged into audit/next.

Thanks.

> diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
> index e867c17d3f84..85a5b306733b 100644
> --- a/kernel/audit_tree.c
> +++ b/kernel/audit_tree.c
> @@ -34,7 +34,7 @@ struct audit_chunk {
>                 struct list_head list;
>                 struct audit_tree *owner;
>                 unsigned index;         /* index; upper bit indicates 'will prune' */
> -       } owners[];
> +       } owners[] __counted_by(count);
>  };
>
>  struct audit_tree_mark {
> --
> 2.34.1

-- 
paul-moore.com

On 8/17/23 14:35, 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 audit_chunk.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Eric Paris <eparis@redhat.com>
> Cc: audit@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> ---
>   kernel/audit_tree.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
> index e867c17d3f84..85a5b306733b 100644
> --- a/kernel/audit_tree.c
> +++ b/kernel/audit_tree.c
> @@ -34,7 +34,7 @@ struct audit_chunk {
>   		struct list_head list;
>   		struct audit_tree *owner;
>   		unsigned index;		/* index; upper bit indicates 'will prune' */
> -	} owners[];
> +	} owners[] __counted_by(count);
>   };
>   
>   struct audit_tree_mark {