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Date: Sun, 28 Feb 2021 18:00:09 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Romain Perier <romain.perier@...il.com>
Cc: Kees Cook <keescook@...omium.org>, 
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Valentina Manea <valentina.manea.m@...il.com>, 
	Shuah Khan <shuah@...nel.org>, Shuah Khan <skhan@...uxfoundation.org>, 
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 19/20] usbip: usbip_host: Manual replacement of the
 deprecated strlcpy() with return values

On Monday, February 22, 2021, Romain Perier <romain.perier@...il.com> 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;
>
>
I’m wondering why you shadow the initial error. Should not be better

if (Len < 0)
  return Len;

?



>         if (!strncmp(buf, "add ", 4)) {
>
>

-- 
With Best Regards,
Andy Shevchenko

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