From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [PATCH v2] usb: typec: tps6598x: Remove VLA usage
Date: Tue, 26 Jun 2018 11:11:01 +0300 [thread overview]
Message-ID: <20180626081101.GE16601@kuha.fi.intel.com> (raw)
In-Reply-To: <20180625222316.GA5773@beast>
On Mon, Jun 25, 2018 at 03:23:16PM -0700, Kees Cook wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> uses the maximum buffer size and adds a sanity check. While 25 bytes
> is the size of the largest current things coming through, Heikki
> Krogerus pointed out that the actual max in 64 bytes, as per ch 1.3.2
> http://www.ti.com/lit/ug/slvuan1a/slvuan1a.pdf
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
> v2: use 64 bytes (Heikki)
> ---
> drivers/usb/typec/tps6598x.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/typec/tps6598x.c b/drivers/usb/typec/tps6598x.c
> index 4b4c8d271b27..c84c8c189e90 100644
> --- a/drivers/usb/typec/tps6598x.c
> +++ b/drivers/usb/typec/tps6598x.c
> @@ -81,12 +81,21 @@ struct tps6598x {
> struct typec_capability typec_cap;
> };
>
> +/*
> + * Max data bytes for Data1, Data2, and other registers. See ch 1.3.2:
> + * http://www.ti.com/lit/ug/slvuan1a/slvuan1a.pdf
> + */
> +#define TPS_MAX_LEN 64
> +
> static int
> tps6598x_block_read(struct tps6598x *tps, u8 reg, void *val, size_t len)
> {
> - u8 data[len + 1];
> + u8 data[TPS_MAX_LEN + 1];
> int ret;
>
> + if (WARN_ON(len + 1 > sizeof(data)))
> + return -EINVAL;
> +
> if (!tps->i2c_protocol)
> return regmap_raw_read(tps->regmap, reg, val, len);
Thanks,
--
heikki
prev parent reply other threads:[~2018-06-26 8:11 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-25 22:23 [PATCH v2] usb: typec: tps6598x: Remove VLA usage Kees Cook
2018-06-26 8:11 ` Heikki Krogerus [this message]
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