linux-hardening - Re: [PATCH] drbd: Annotate struct fifo_buffer with __counted

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Message-ID: <c2c552ff-c650-1e69-b552-f6f872605526@embeddedor.com>
Date:   Fri, 15 Sep 2023 14:24:35 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Kees Cook <keescook@...omium.org>,
        Philipp Reisner <philipp.reisner@...bit.com>
Cc:     Lars Ellenberg <lars.ellenberg@...bit.com>,
        Christoph Böhmwalder 
        <christoph.boehmwalder@...bit.com>, Jens Axboe <axboe@...nel.dk>,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] drbd: Annotate struct fifo_buffer with __counted_by



On 9/15/23 14:03, 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 fifo_buffer.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Philipp Reisner <philipp.reisner@...bit.com>
> Cc: Lars Ellenberg <lars.ellenberg@...bit.com>
> Cc: "Christoph Böhmwalder" <christoph.boehmwalder@...bit.com>
> Cc: Jens Axboe <axboe@...nel.dk>
> Cc: drbd-dev@...ts.linbit.com
> Cc: linux-block@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>

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

Thanks
-- 
Gustavo

> ---
>   drivers/block/drbd/drbd_int.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
> index a30a5ed811be..7eecc53fae3d 100644
> --- a/drivers/block/drbd/drbd_int.h
> +++ b/drivers/block/drbd/drbd_int.h
> @@ -553,7 +553,7 @@ struct fifo_buffer {
>   	unsigned int head_index;
>   	unsigned int size;
>   	int total; /* sum of all values */
> -	int values[];
> +	int values[] __counted_by(size);
>   };
>   extern struct fifo_buffer *fifo_alloc(unsigned int fifo_size);
>