[PATCH] aio: Annotate struct kioctx_table with __counted_by

[PATCH] aio: Annotate struct kioctx_table 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 kioctx_table.

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

Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-aio@kvack.org
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/aio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/aio.c b/fs/aio.c
index a4c2a6bac72c..f8589caef9c1 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -80,7 +80,7 @@ struct aio_ring {
 struct kioctx_table {
 	struct rcu_head		rcu;
 	unsigned		nr;
-	struct kioctx __rcu	*table[];
+	struct kioctx __rcu	*table[] __counted_by(nr);
 };
 
 struct kioctx_cpu {
-- 
2.34.1

Re: [PATCH] aio: Annotate struct kioctx_table 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 kioctx_table.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Benjamin LaHaise <bcrl@kvack.org>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: linux-aio@kvack.org
> Cc: linux-fsdevel@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   fs/aio.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/aio.c b/fs/aio.c
> index a4c2a6bac72c..f8589caef9c1 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -80,7 +80,7 @@ struct aio_ring {
>   struct kioctx_table {
>   	struct rcu_head		rcu;
>   	unsigned		nr;
> -	struct kioctx __rcu	*table[];
> +	struct kioctx __rcu	*table[] __counted_by(nr);
>   };
>   
>   struct kioctx_cpu {

Re: [PATCH] aio: Annotate struct kioctx_table with __counted_by

[Christian Brauner]

On Fri, 15 Sep 2023 13:14:14 -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 kioctx_table.
> 
> [...]

Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.misc

[1/1] aio: Annotate struct kioctx_table with __counted_by
      https://git.kernel.org/vfs/vfs/c/7f3782aef7e6