[PATCH] afs: Annotate struct afs_permits with __counted_by

[PATCH] afs: Annotate struct afs_permits 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 afs_permits.

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

Cc: David Howells <dhowells@redhat.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: linux-afs@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/afs/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 07433a5349ca..469a717467a4 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -705,7 +705,7 @@ struct afs_permits {
 	refcount_t		usage;
 	unsigned short		nr_permits;	/* Number of records */
 	bool			invalidated;	/* Invalidated due to key change */
-	struct afs_permit	permits[];	/* List of permits sorted by key pointer */
+	struct afs_permit	permits[] __counted_by(nr_permits);	/* List of permits sorted by key pointer */
 };
 
 /*
-- 
2.34.1

Re: [PATCH] afs: Annotate struct afs_permits with __counted_by

[Gustavo A. R. Silva]

On 9/15/23 14:14, 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 afs_permits.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: David Howells <dhowells@redhat.com>
> Cc: Marc Dionne <marc.dionne@auristor.com>
> Cc: linux-afs@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   fs/afs/internal.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/afs/internal.h b/fs/afs/internal.h
> index 07433a5349ca..469a717467a4 100644
> --- a/fs/afs/internal.h
> +++ b/fs/afs/internal.h
> @@ -705,7 +705,7 @@ struct afs_permits {
>   	refcount_t		usage;
>   	unsigned short		nr_permits;	/* Number of records */
>   	bool			invalidated;	/* Invalidated due to key change */
> -	struct afs_permit	permits[];	/* List of permits sorted by key pointer */
> +	struct afs_permit	permits[] __counted_by(nr_permits);	/* List of permits sorted by key pointer */
>   };
>   
>   /*

Re: [PATCH] afs: Annotate struct afs_permits with __counted_by

[Kees Cook]

On Fri, 15 Sep 2023 13:14:56 -0700, 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 afs_permits.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] afs: Annotate struct afs_permits with __counted_by
      https://git.kernel.org/kees/c/45faff97751a

Take care,

-- 
Kees Cook