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Message-ID: <1bcde585-f740-8959-6e2e-19793795b60e@embeddedor.com>
Date: Sun, 1 Oct 2023 09:49:16 +0200
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>,
Miquel Raynal <miquel.raynal@...tlin.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
Heiko Stuebner <heiko@...ech.de>,
Kees Cook <keescook@...omium.org>,
"Gustavo A. R. Silva" <gustavoars@...nel.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
linux-mtd@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org,
linux-rockchip@...ts.infradead.org,
linux-hardening@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] mtd: rawnand: rockchip: Use struct_size()
On 10/1/23 09:44, Christophe JAILLET wrote:
> Use struct_size() instead of hand writing it.
> This is less verbose and more robust.
>
> While at it, 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).
Again, I'd prefer this as two separate patches.
>
> Also remove a useless comment about the position of a flex-array in a
> structure.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
In any case:
Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Thanks
--
Gustavo
> ---
> This patch is part of a work done in parallel of what is currently worked
> on by Kees Cook.
>
> My patches are only related to corner cases that do NOT match the
> semantic of his Coccinelle script[1].
>
> In this case, struct_size() was not used to compute the size needed for the
> structure and its flex array.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> ---
> drivers/mtd/nand/raw/rockchip-nand-controller.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/rockchip-nand-controller.c b/drivers/mtd/nand/raw/rockchip-nand-controller.c
> index 5bc90ffa721f..596cf9a78274 100644
> --- a/drivers/mtd/nand/raw/rockchip-nand-controller.c
> +++ b/drivers/mtd/nand/raw/rockchip-nand-controller.c
> @@ -158,8 +158,7 @@ struct rk_nfc_nand_chip {
> u32 timing;
>
> u8 nsels;
> - u8 sels[];
> - /* Nothing after this field. */
> + u8 sels[] __counted_by(nsels);
> };
>
> struct rk_nfc {
> @@ -1119,7 +1118,7 @@ static int rk_nfc_nand_chip_init(struct device *dev, struct rk_nfc *nfc,
> return -EINVAL;
> }
>
> - rknand = devm_kzalloc(dev, sizeof(*rknand) + nsels * sizeof(u8),
> + rknand = devm_kzalloc(dev, struct_size(rknand, sels, nsels),
> GFP_KERNEL);
> if (!rknand)
> return -ENOMEM;
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