linux-kernel - Re: [PATCH v2 3/7] test_firmware: add partial read support for request_firmware_into

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Message-ID: <20200220084255.GW7838@kadam>
Date:   Thu, 20 Feb 2020 11:42:55 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Scott Branden <scott.branden@...adcom.com>
Cc:     Luis Chamberlain <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        David Brown <david.brown@...aro.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Shuah Khan <shuah@...nel.org>, bjorn.andersson@...aro.org,
        Shuah Khan <skhan@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        Olof Johansson <olof@...om.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Colin Ian King <colin.king@...onical.com>,
        Kees Cook <keescook@...omium.org>,
        Takashi Iwai <tiwai@...e.de>, linux-kselftest@...r.kernel.org,
        Andy Gross <agross@...nel.org>
Subject: Re: [PATCH v2 3/7] test_firmware: add partial read support for
 request_firmware_into_buf

On Wed, Feb 19, 2020 at 04:48:21PM -0800, Scott Branden wrote:
> +static int test_dev_config_update_size_t(const char *buf,
> +					 size_t size,
> +					 size_t *cfg)
> +{
> +	int ret;
> +	long new;
> +
> +	ret = kstrtol(buf, 10, &new);
> +	if (ret)
> +		return ret;
> +
> +	if (new > SIZE_MAX)

This "new" variable is long and SIZE_MAX is ULONG_MAX so the condition
can't be true.

> +		return -EINVAL;
> +
> +	mutex_lock(&test_fw_mutex);
> +	*(size_t *)cfg = new;
> +	mutex_unlock(&test_fw_mutex);
> +
> +	/* Always return full write size even if we didn't consume all */
> +	return size;
> +}
> +
> +static ssize_t test_dev_config_show_size_t(char *buf, int cfg)
> +{
> +	size_t val;
> +
> +	mutex_lock(&test_fw_mutex);
> +	val = cfg;
> +	mutex_unlock(&test_fw_mutex);

Both val and cfg are stack variables so there is no need for locking.
Probably you meant to pass a pointer to cfg?

> +
> +	return snprintf(buf, PAGE_SIZE, "%zu\n", val);
> +}
> +
>  static ssize_t test_dev_config_show_int(char *buf, int cfg)
>  {
>  	int val;

regards,
dan carpenter