[PATCH] watch_queue: Annotate struct watch_filter with __counted_by

[PATCH] watch_queue: Annotate struct watch_filter 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 watch_filter.

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

Cc: David Howells <dhowells@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Siddh Raman Pant <code@siddh.me>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Qian Cai <cai@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/linux/watch_queue.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/watch_queue.h b/include/linux/watch_queue.h
index 45cd42f55d49..429c7b6afead 100644
--- a/include/linux/watch_queue.h
+++ b/include/linux/watch_queue.h
@@ -32,7 +32,7 @@ struct watch_filter {
 		DECLARE_BITMAP(type_filter, WATCH_TYPE__NR);
 	};
 	u32			nr_filters;	/* Number of filters */
-	struct watch_type_filter filters[];
+	struct watch_type_filter filters[] __counted_by(nr_filters);
 };
 
 struct watch_queue {
-- 
2.34.1

Re: [PATCH] watch_queue: Annotate struct watch_filter with __counted_by

[Siddh Raman Pant]

On Fri, 22 Sep 2023 23:24:08 +0530, 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 watch_filter.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: David Howells <dhowells@redhat.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Siddh Raman Pant <code@siddh.me>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Qian Cai <cai@redhat.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>

Tested with keyutils testsuite.

Tested-by: Siddh Raman Pant <code@siddh.me>

Thanks,
Siddh

> ---
>  include/linux/watch_queue.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/watch_queue.h b/include/linux/watch_queue.h
> index 45cd42f55d49..429c7b6afead 100644
> --- a/include/linux/watch_queue.h
> +++ b/include/linux/watch_queue.h
> @@ -32,7 +32,7 @@ struct watch_filter {
>  		DECLARE_BITMAP(type_filter, WATCH_TYPE__NR);
>  	};
>  	u32			nr_filters;	/* Number of filters */
> -	struct watch_type_filter filters[];
> +	struct watch_type_filter filters[] __counted_by(nr_filters);
>  };
>  
>  struct watch_queue {
> -- 
> 2.34.1

Re: [PATCH] watch_queue: Annotate struct watch_filter with __counted_by

[Gustavo A. R. Silva]

On 9/22/23 11:54, 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 watch_filter.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: David Howells <dhowells@redhat.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Siddh Raman Pant <code@siddh.me>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Qian Cai <cai@redhat.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   include/linux/watch_queue.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/watch_queue.h b/include/linux/watch_queue.h
> index 45cd42f55d49..429c7b6afead 100644
> --- a/include/linux/watch_queue.h
> +++ b/include/linux/watch_queue.h
> @@ -32,7 +32,7 @@ struct watch_filter {
>   		DECLARE_BITMAP(type_filter, WATCH_TYPE__NR);
>   	};
>   	u32			nr_filters;	/* Number of filters */
> -	struct watch_type_filter filters[];
> +	struct watch_type_filter filters[] __counted_by(nr_filters);
>   };
>   
>   struct watch_queue {

Re: [PATCH] watch_queue: Annotate struct watch_filter with __counted_by

[Christian Brauner]

On Fri, 22 Sep 2023 10:54:08 -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 watch_filter.
> 
> [...]

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] watch_queue: Annotate struct watch_filter with __counted_by
      https://git.kernel.org/vfs/vfs/c/6b601adb5e79