linux-kernel - Re: [PATCH 19/20] usbip: usbip_host: Manual replacement of the deprecated strlcpy() with return values

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Message-ID: <0323dcb2-726c-7ea2-8e8b-dba81090b571@linuxfoundation.org>
Date:   Mon, 22 Feb 2021 09:21:50 -0700
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Romain Perier <romain.perier@...il.com>,
        Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Valentina Manea <valentina.manea.m@...il.com>,
        Shuah Khan <shuah@...nel.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 19/20] usbip: usbip_host: Manual replacement of the
 deprecated strlcpy() with return values

On 2/22/21 8:12 AM, Romain Perier wrote:
> The strlcpy() reads the entire source buffer first, it is dangerous if
> the source buffer lenght is unbounded or possibility non NULL-terminated.
> It can lead to linear read overflows, crashes, etc...
> 
> As recommended in the deprecated interfaces [1], it should be replaced
> by strscpy.
> 
> This commit replaces all calls to strlcpy that handle the return values
> by the corresponding strscpy calls with new handling of the return
> values (as it is quite different between the two functions).
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> 
> Signed-off-by: Romain Perier <romain.perier@...il.com>
> ---
>   drivers/usb/usbip/stub_main.c |    6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c
> index 77a5b3f8736a..5bc2c09c0d10 100644
> --- a/drivers/usb/usbip/stub_main.c
> +++ b/drivers/usb/usbip/stub_main.c
> @@ -167,15 +167,15 @@ static ssize_t match_busid_show(struct device_driver *drv, char *buf)
>   static ssize_t match_busid_store(struct device_driver *dev, const char *buf,
>   				 size_t count)
>   {
> -	int len;
> +	ssize_t len;
>   	char busid[BUSID_SIZE];
>   
>   	if (count < 5)
>   		return -EINVAL;
>   
>   	/* busid needs to include \0 termination */
> -	len = strlcpy(busid, buf + 4, BUSID_SIZE);
> -	if (sizeof(busid) <= len)
> +	len = strscpy(busid, buf + 4, BUSID_SIZE);
> +	if (len == -E2BIG)
>   		return -EINVAL;
>   
>   	if (!strncmp(buf, "add ", 4)) {
> 


Looks good to me. Thank you.

Acked-by: Shuah Khan <skhan@...uxfoundation.org>

thanks,
-- Shuah