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Message-ID: <31d9e182-8f8d-b47a-a9f3-db1b7df5bb38@embeddedor.com>
Date: Sat, 23 Sep 2023 10:26:43 -0600
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Kees Cook <keescook@...omium.org>,
Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: Peter Rosin <peda@...ntia.se>, linux-i2c@...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] i2c: mux: demux-pinctrl: Annotate struct
i2c_demux_pinctrl_priv with __counted_by
On 9/22/23 11:49, 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 i2c_demux_pinctrl_priv.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>
> Cc: Peter Rosin <peda@...ntia.se>
> Cc: linux-i2c@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Thanks
--
Gustavo
> ---
> drivers/i2c/muxes/i2c-demux-pinctrl.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
> index a3a122fae71e..5e15d8777229 100644
> --- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
> +++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
> @@ -32,7 +32,7 @@ struct i2c_demux_pinctrl_priv {
> const char *bus_name;
> struct i2c_adapter cur_adap;
> struct i2c_algorithm algo;
> - struct i2c_demux_pinctrl_chan chan[];
> + struct i2c_demux_pinctrl_chan chan[] __counted_by(num_chan);
> };
>
> static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> @@ -226,6 +226,8 @@ static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
> if (!priv || !props)
> return -ENOMEM;
>
> + priv->num_chan = num_chan;
> +
> err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
> if (err)
> return err;
> @@ -248,8 +250,6 @@ static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
> of_changeset_init(&priv->chan[i].chgset);
> of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
> }
> -
> - priv->num_chan = num_chan;
> priv->dev = &pdev->dev;
>
> platform_set_drvdata(pdev, priv);
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