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References: <20220513044143.1045728-1-tzungbi@kernel.org> <20220513044143.1045728-8-tzungbi@kernel.org>
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From:   Guenter Roeck <groeck@google.com>
Date:   Fri, 13 May 2022 06:20:36 -0700
Message-ID: <CABXOdTft-YJHJNiw2xnigHsySOjJ1dDwFoQwXDiMADN5O2Loog@mail.gmail.com>
Subject: Re: [PATCH v2 7/7] platform/chrome: cros_ec_spi: drop BUG_ON() if
 `din` isn't large enough
To:     Tzung-Bi Shih <tzungbi@kernel.org>
Cc:     Benson Leung <bleung@chromium.org>,
        Guenter Roeck <groeck@chromium.org>,
        chrome-platform@lists.linux.dev,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Thu, May 12, 2022 at 9:42 PM Tzung-Bi Shih <tzungbi@kernel.org> wrote:
>
> It is overkill to crash the kernel if the `din` buffer is going to full
> or overflow.
>
> Drop the BUG_ON() and return -EINVAL instead.
>
> Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

Reviewed-by: Guenter Roeck <groeck@chromium.org>

> ---
> Changes from v1:
> - Separate from the original 6th patch.
>
>  drivers/platform/chrome/cros_ec_spi.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
> index 5264615f46af..7360b3ff6e4f 100644
> --- a/drivers/platform/chrome/cros_ec_spi.c
> +++ b/drivers/platform/chrome/cros_ec_spi.c
> @@ -160,7 +160,8 @@ static int receive_n_bytes(struct cros_ec_device *ec_dev, u8 *buf, int n)
>         struct spi_message msg;
>         int ret;
>
> -       BUG_ON(buf - ec_dev->din + n > ec_dev->din_size);
> +       if (buf - ec_dev->din + n > ec_dev->din_size)
> +               return -EINVAL;
>
>         memset(&trans, 0, sizeof(trans));
>         trans.cs_change = 1;
> @@ -197,7 +198,8 @@ static int cros_ec_spi_receive_packet(struct cros_ec_device *ec_dev,
>         unsigned long deadline;
>         int todo;
>
> -       BUG_ON(ec_dev->din_size < EC_MSG_PREAMBLE_COUNT);
> +       if (ec_dev->din_size < EC_MSG_PREAMBLE_COUNT)
> +               return -EINVAL;
>
>         /* Receive data until we see the header byte */
>         deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
> @@ -304,7 +306,8 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
>         unsigned long deadline;
>         int todo;
>
> -       BUG_ON(ec_dev->din_size < EC_MSG_PREAMBLE_COUNT);
> +       if (ec_dev->din_size < EC_MSG_PREAMBLE_COUNT)
> +               return -EINVAL;
>
>         /* Receive data until we see the header byte */
>         deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
> --
> 2.36.0.550.gb090851708-goog
>