Re: [PATCH] selinux: Annotate struct sidtab_str_cache with __counted_by

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

On 8/17/23 14:22, 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 sidtab_str_cache.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
> Cc: Eric Paris <eparis@parisplace.org>
> Cc: Ondrej Mosnacek <omosnace@redhat.com>
> Cc: selinux@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
--
Gustavo

> ---
>   security/selinux/ss/sidtab.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c
> index d8ead463b8df..732fd8e22a12 100644
> --- a/security/selinux/ss/sidtab.c
> +++ b/security/selinux/ss/sidtab.c
> @@ -25,7 +25,7 @@ struct sidtab_str_cache {
>   	struct list_head lru_member;
>   	struct sidtab_entry *parent;
>   	u32 len;
> -	char str[];
> +	char str[] __counted_by(len);
>   };
>   
>   #define index_to_sid(index) ((index) + SECINITSID_NUM + 1)