[Lucid,CVE-2013-2852] b43: stop format string leaking into error msgs

From: Kees Cook <keescook@chromium.org>

BugLink: https://bugs.launchpad.net/bugs/1189833

The module parameter "fwpostfix" is userspace controllable, unfiltered,
and is used to define the firmware filename. b43_do_request_fw() populates
ctx->errors[] on error, containing the firmware filename. b43err()
parses its arguments as a format string. For systems with b43 hardware,
this could lead to a uid-0 to ring-0 escalation.

CVE-2013-2852

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>
(cherry picked from commit e0e29b683d6784ef59bbc914eac85a04b650e63c)

Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/net/wireless/b43/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On Thu, Jun 20, 2013 at 12:31:37PM +0100, Luis Henriques wrote:
> From: Kees Cook <keescook@chromium.org>
> 
> BugLink: https://bugs.launchpad.net/bugs/1189833
> 
> The module parameter "fwpostfix" is userspace controllable, unfiltered,
> and is used to define the firmware filename. b43_do_request_fw() populates
> ctx->errors[] on error, containing the firmware filename. b43err()
> parses its arguments as a format string. For systems with b43 hardware,
> this could lead to a uid-0 to ring-0 escalation.
> 
> CVE-2013-2852
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Cc: stable@vger.kernel.org
> Signed-off-by: John W. Linville <linville@tuxdriver.com>
> (cherry picked from commit e0e29b683d6784ef59bbc914eac85a04b650e63c)
> 
> Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
> ---
>  drivers/net/wireless/b43/main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c
> index 9bd5366..c14acea 100644
> --- a/drivers/net/wireless/b43/main.c
> +++ b/drivers/net/wireless/b43/main.c
> @@ -2287,7 +2287,7 @@ static int b43_request_firmware(struct b43_wldev *dev)
>  	for (i = 0; i < B43_NR_FWTYPES; i++) {
>  		errmsg = ctx->errors[i];
>  		if (strlen(errmsg))
> -			b43err(dev->wl, errmsg);
> +			b43err(dev->wl, "%s", errmsg);
>  	}
>  	b43_print_fw_helptext(dev->wl, 1);
>  	err = -ENOENT;

Looks to do what is claimed, clean cherrypick.

Acked-by: Andy Whitcroft <apw@canonical.com>

Is this coming via stable for later releases?

-apw