From: Phil Reid <preid@electromag.com.au>
To: Laura Abbott <labbott@redhat.com>,
Linus Walleij <linus.walleij@linaro.org>,
Kees Cook <keescook@chromium.org>,
Patrice Chotard <patrice.chotard@st.com>
Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com
Subject: Re: [PATCHv2 4/4] gpio: Remove VLA from stmpe driver
Date: Mon, 19 Mar 2018 09:29:59 +0800 [thread overview]
Message-ID: <21a2e869-62fb-75ef-ae7b-a27e136696f7@electromag.com.au> (raw)
In-Reply-To: <20180315180030.20001-5-labbott@redhat.com>
On 16/03/2018 02:00, Laura Abbott wrote:
> The new challenge is to remove VLAs from the kernel
> (see https://lkml.org/lkml/2018/3/7/621)
>
> This patch replaces a VLA with an appropriate call to kmalloc_array.
>
> Signed-off-by: Laura Abbott <labbott@redhat.com>
> ---
> v2: Switch to GFP_KERNEL. There was some discussion about if we should
> be doing the allocation at all but given a) the allocation is pretty
> small and b) we can possibly take a mutex in a called function I think
> this is fine.
I still think it's a bad idea. It's simple to preallocate the buffer.
But it's up to the maintainer.
> ---
> drivers/gpio/gpio-stmpe.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-stmpe.c b/drivers/gpio/gpio-stmpe.c
> index f8d7d1cd8488..c2bb20ace6f5 100644
> --- a/drivers/gpio/gpio-stmpe.c
> +++ b/drivers/gpio/gpio-stmpe.c
> @@ -369,10 +369,14 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
> struct stmpe *stmpe = stmpe_gpio->stmpe;
> u8 statmsbreg;
> int num_banks = DIV_ROUND_UP(stmpe->num_gpios, 8);
> - u8 status[num_banks];
> + u8 *status;
> int ret;
> int i;
>
> + status = kmalloc_array(num_banks, sizeof(*status), GFP_KERNEL);
> + if (!status)
> + return IRQ_NONE;
> +
> /*
> * the stmpe_block_read() call below, imposes to set statmsbreg
> * with the register located at the lowest address. As STMPE1600
> @@ -424,6 +428,7 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
> }
> }
>
> + kfree(status);
> return IRQ_HANDLED;
> }
>
>
--
Regards
Phil Reid
next prev parent reply other threads:[~2018-03-19 1:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-15 18:00 [PATCHv2 0/4] VLA removal from the gpio subsystem Laura Abbott
2018-03-15 18:00 ` [PATCHv2 1/4] gpio: Remove VLA from gpiolib Laura Abbott
2018-03-17 15:36 ` kbuild test robot
2018-03-15 18:00 ` [PATCHv2 2/4] gpio: Remove VLA from MAX3191X driver Laura Abbott
2018-03-19 14:38 ` Lukas Wunner
2018-03-15 18:00 ` [PATCHv2 3/4] gpio: Remove VLA from xra1403 driver Laura Abbott
2018-03-15 18:00 ` [PATCHv2 4/4] gpio: Remove VLA from stmpe driver Laura Abbott
2018-03-19 1:29 ` Phil Reid [this message]
2018-03-22 21:43 ` Laura Abbott
2018-03-23 1:28 ` Phil Reid
2018-03-27 13:41 ` Linus Walleij
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