linux-hardening - Re: [PATCH][next] btrfs: Add __counted_by for struct btrfs_delayed_item and use struct

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Message-ID: <202310091409.6F3B10C@keescook>
Date: Mon, 9 Oct 2023 14:10:01 -0700
From: Kees Cook <keescook@...omium.org>
To: "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>,
	David Sterba <dsterba@...e.com>, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH][next] btrfs: Add __counted_by for struct
 btrfs_delayed_item and use struct_size()

On Mon, Oct 09, 2023 at 02:44:54PM -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).
> 
> While there, use struct_size() helper, instead of the open-coded
> version, to calculate the size for the allocation of the whole
> flexible structure, including of course, the flexible-array member.
> 
> This code was found with the help of Coccinelle, and audited and
> fixed manually.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Looks right to me.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook