Received-SPF: pass (google.com: domain of linux-kernel+bounces-157440-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Wed, 24 Apr 2024 21:06:50 +0300
From: Fedor Pchelkin <pchelkin@ispras.ru>
To: Roman Smirnov <r.smirnov@omp.ru>
Cc: Michael Krufky <mkrufky@linuxtv.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Jia-Ju Bai <baijiaju1990@gmail.com>,
	Hans Verkuil <hverkuil-cisco@xs4all.nl>,
	lvc-project@linuxtesting.org, Sergey Shtylyov <s.shtylyov@omp.ru>,
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [lvc-project] [PATCH 1/3] media: tuners: tda18271: fix error
 code handling in tda18271_attach()
Message-ID: <20240424180650.tpemkolglnkb2pyn@fpc>
References: <20240416114509.198069-1-r.smirnov@omp.ru>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20240416114509.198069-1-r.smirnov@omp.ru>

Hello Roman,

On Tue, 16. Apr 14:45, Roman Smirnov wrote:
> tda18271_attach() uses the hybrid_tuner_request_state() macro.
> It may return the error code -ENOMEM, but the function handle
> the value 0 instead.

Maybe hybrid_tuner_request_state macro declaration should be fixed to
generate zero in case of a memory allocation failure?

At least it has a comment stating the following
 * 0 - no instances, indicates an error - kzalloc must have failed

And supposedly a number of drivers implemented the error handling based on
this assumption.

The drivers mentioned in this series are not the only ones susceptible to
the problem. Grepping through "hybrid_tuner_request_state" calls also gives
out tda9887, xc2028, r820t and others.

> 
> Found by Linux Verification Center (linuxtesting.org) with Svace.
> 
> Fixes: b9302fa7ed97 ("media: tuners: fix error return code of hybrid_tuner_request_state()")
> Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
> ---
>  drivers/media/tuners/tda18271-fe.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/tuners/tda18271-fe.c b/drivers/media/tuners/tda18271-fe.c
> index a7e721baaa99..23432210f06a 100644
> --- a/drivers/media/tuners/tda18271-fe.c
> +++ b/drivers/media/tuners/tda18271-fe.c
> @@ -1255,7 +1255,7 @@ struct dvb_frontend *tda18271_attach(struct dvb_frontend *fe, u8 addr,
>  					      hybrid_tuner_instance_list,
>  					      i2c, addr, "tda18271");
>  	switch (instance) {
> -	case 0:
> +	case -ENOMEM:
>  		goto fail;
>  	case 1:
>  		/* new tuner instance */
> -- 
> 2.34.1
>