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Message-ID: <CAHC9VhR-vxsaR7deTQ+zzVP9W2uSupz4ucf8p+tt0e730qbZ1g@mail.gmail.com>
Date: Fri, 18 Aug 2023 12:25:12 -0400
From: Paul Moore <paul@...l-moore.com>
To: Kees Cook <keescook@...omium.org>
Cc: Stephen Smalley <stephen.smalley.work@...il.com>,
Eric Paris <eparis@...isplace.org>,
Ondrej Mosnacek <omosnace@...hat.com>, selinux@...r.kernel.org,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>,
"GONG, Ruiqi" <gongruiqi1@...wei.com>,
linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
linux-hardening@...r.kernel.org
Subject: Re: [PATCH] selinux: Annotate struct sidtab_str_cache with __counted_by
On Thu, Aug 17, 2023 at 4:22 PM Kees Cook <keescook@...omium.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 sidtab_str_cache.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Paul Moore <paul@...l-moore.com>
> Cc: Stephen Smalley <stephen.smalley.work@...il.com>
> Cc: Eric Paris <eparis@...isplace.org>
> Cc: Ondrej Mosnacek <omosnace@...hat.com>
> Cc: selinux@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
> security/selinux/ss/sidtab.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
This also looks good to me, but similarly to the audit patch, since we
are at -rc6 I'm going to wait to merge this until after the merge
window. I'll send a follow up email once it's merged.
Thanks.
> 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)
> --
> 2.34.1
--
paul-moore.com
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