linux-kernel - Re: [PATCH][V2] dvb_frontend: ensure that inital front end status initialized

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Date:   Thu, 20 Jul 2017 20:35:37 -0300
From:   Mauro Carvalho Chehab <mchehab@...pensource.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Max Kellermann <max.kellermann@...il.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Markus Elfring <elfring@...rs.sourceforge.net>,
        Ingo Molnar <mingo@...nel.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Shuah Khan <shuah@...nel.org>, linux-media@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][V2] dvb_frontend: ensure that inital front end status
 initialized

Em Thu, 20 Jul 2017 23:12:07 +0100
Colin King <colin.king@...onical.com> escreveu:

> From: Colin Ian King <colin.king@...onical.com>
> 
> The fe_status variable s is not initialized meaning it can have any
> random garbage status.  This could be problematic if fe->ops.tune is
> false as s is not updated by the call to fe->ops.tune() and a
> subsequent check on the change status will using a garbage value.
> Fix this by adding FE_NONE to the enum fe_status and initializing
> s to this.
> 
> Detected by CoverityScan, CID#112887 ("Uninitialized scalar variable")
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/media/dvb-core/dvb_frontend.c | 2 +-
>  include/uapi/linux/dvb/frontend.h     | 1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
> index e3fff8f64d37..18cc3bbc699c 100644
> --- a/drivers/media/dvb-core/dvb_frontend.c
> +++ b/drivers/media/dvb-core/dvb_frontend.c
> @@ -631,7 +631,7 @@ static int dvb_frontend_thread(void *data)
>  	struct dvb_frontend *fe = data;
>  	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
>  	struct dvb_frontend_private *fepriv = fe->frontend_priv;
> -	enum fe_status s;
> +	enum fe_status s = FE_NONE;
>  	enum dvbfe_algo algo;
>  	bool re_tune = false;
>  	bool semheld = false;
> diff --git a/include/uapi/linux/dvb/frontend.h b/include/uapi/linux/dvb/frontend.h
> index 00a20cd21ee2..afc3972b0879 100644
> --- a/include/uapi/linux/dvb/frontend.h
> +++ b/include/uapi/linux/dvb/frontend.h
> @@ -127,6 +127,7 @@ enum fe_sec_mini_cmd {
>   *			to reset DiSEqC, tone and parameters
>   */
>  enum fe_status {
> +	FE_NONE			= 0x00,
>  	FE_HAS_SIGNAL		= 0x01,
>  	FE_HAS_CARRIER		= 0x02,
>  	FE_HAS_VITERBI		= 0x04,

If you're willing to touch the uAPI, please update its documentation:

$ git grep FE_HAS_SIGNAL Documentation/
Documentation/media/uapi/dvb/examples.rst:       if (*stat & FE_HAS_SIGNAL)
Documentation/media/uapi/dvb/fe-read-status.rst:          ``FE_HAS_SIGNAL``


Regards,
Mauro

Thanks,
Mauro