2024-05-01 17:02:45

by Erick Archer

Subject: [PATCH] sctp: annotate struct sctp_assoc_ids with __counted_by()

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 via
CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
(for strcpy/memcpy-family functions).

Suggested-by: Kees Cook <[email protected]>
Signed-off-by: Erick Archer <[email protected]>
---
include/uapi/linux/sctp.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
index b7d91d4cf0db..836173e73401 100644
--- a/include/uapi/linux/sctp.h
+++ b/include/uapi/linux/sctp.h
@@ -1007,7 +1007,7 @@ enum sctp_sstat_state {
*/
struct sctp_assoc_ids {
__u32 gaids_number_of_ids;
- sctp_assoc_t gaids_assoc_id[];
+ sctp_assoc_t gaids_assoc_id[] __counted_by(gaids_number_of_ids);
};

/*
--
2.25.1

2024-05-01 20:04:24

by Justin Stitt

Subject: Re: [PATCH] sctp: annotate struct sctp_assoc_ids with __counted_by()

Hi,

On Wed, May 01, 2024 at 07:01:22PM +0200, Erick Archer 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 via
> CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
> (for strcpy/memcpy-family functions).
>
> Suggested-by: Kees Cook <[email protected]>
> Signed-off-by: Erick Archer <[email protected]>
> ---
> include/uapi/linux/sctp.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
> index b7d91d4cf0db..836173e73401 100644
> --- a/include/uapi/linux/sctp.h
> +++ b/include/uapi/linux/sctp.h
> @@ -1007,7 +1007,7 @@ enum sctp_sstat_state {
> */
> struct sctp_assoc_ids {
> __u32 gaids_number_of_ids;
> - sctp_assoc_t gaids_assoc_id[];
> + sctp_assoc_t gaids_assoc_id[] __counted_by(gaids_number_of_ids);

Crucially, gaids_number_of_ids is assigned before any accesses to
gaids_assoc_id[] are made.

| ids->gaids_number_of_ids = num;
| num = 0;
| list_for_each_entry(asoc, &(sp->ep->asocs), asocs) {
| ids->gaids_assoc_id[num++] = asoc->assoc_id;
| }

So this looks good to me.

Reviewed-by: Justin Stitt <[email protected]>

> };
>
> /*
> --
> 2.25.1
>

Thanks
Justin

2024-05-01 20:06:21

by Kees Cook

Subject: Re: [PATCH] sctp: annotate struct sctp_assoc_ids with __counted_by()

On Wed, May 01, 2024 at 07:01:22PM +0200, Erick Archer 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 via
> CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
> (for strcpy/memcpy-family functions).
>
> Suggested-by: Kees Cook <[email protected]>
> Signed-off-by: Erick Archer <[email protected]>

Thanks!

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook

2024-06-01 14:02:53

by Erick Archer

Subject: Re: [PATCH] sctp: annotate struct sctp_assoc_ids with __counted_by()

Hi,

On Wed, May 01, 2024 at 07:01:22PM +0200, Erick Archer 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 via
> CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
> (for strcpy/memcpy-family functions).
>
> Suggested-by: Kees Cook <[email protected]>
> Signed-off-by: Erick Archer <[email protected]>
> ---
> include/uapi/linux/sctp.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
> index b7d91d4cf0db..836173e73401 100644
> --- a/include/uapi/linux/sctp.h
> +++ b/include/uapi/linux/sctp.h
> @@ -1007,7 +1007,7 @@ enum sctp_sstat_state {
> */
> struct sctp_assoc_ids {
> __u32 gaids_number_of_ids;
> - sctp_assoc_t gaids_assoc_id[];
> + sctp_assoc_t gaids_assoc_id[] __counted_by(gaids_number_of_ids);
> };
>
> /*

Friendly ping: who can take this, please?

Regards,
Erick