Subject: Re: [PATCH][next] Bluetooth: hci_conn: Use __counted_by() and avoid -Wfamnae warning

From: Kees Cook <[email-masked]>
Date: Thu, 2 May 2024 10:45:44 -0700

On Thu, May 02, 2024 at 10:22:00AM -0600, Gustavo A. R. Silva 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).
> 
> Also, -Wflex-array-member-not-at-end is coming in GCC-14, and we are
> getting ready to enable it globally.
> 
> So, use the `DEFINE_FLEX()` helper for an on-stack definition of
> a flexible structure where the size of the flexible-array member
> is known at compile-time, and refactor the rest of the code,
> accordingly.
> 
> With these changes, fix the following warning:
> net/bluetooth/hci_conn.c:669:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
> 
> Link: https://github.com/KSPP/linux/issues/202
> Signed-off-by: Gustavo A. R. Silva <[email-masked]>

Nice! This looks really clean; I'll point people at this patch when they
want to see these kinds of conversions. It has it all! :)

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

-- 
Kees Cook