Date:   Mon, 20 Mar 2023 08:55:51 +0300
From:   Dan Carpenter <error27@gmail.com>
To:     oe-kbuild@lists.linux.dev, Sherry Sun <sherry.sun@nxp.com>,
        gregkh@linuxfoundation.org, jirislaby@kernel.org, robh@kernel.org
Cc:     lkp@intel.com, oe-kbuild-all@lists.linux.dev,
        linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-imx@nxp.com
Subject: Re: [PATCH] tty: serdev: serdev-ttyport: add devt for ctrl->dev
Message-ID: <d2c39186-9641-4aaa-90cb-bce92b2331f6@kili.mountain>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230315105400.23426-1-sherry.sun@nxp.com>
Precedence: bulk

Hi Sherry,

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sherry-Sun/tty-serdev-serdev-ttyport-add-devt-for-ctrl-dev/20230315-185913
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
patch link:    https://lore.kernel.org/r/20230315105400.23426-1-sherry.sun%40nxp.com
patch subject: [PATCH] tty: serdev: serdev-ttyport: add devt for ctrl->dev
config: x86_64-randconfig-m001 (https://download.01.org/0day-ci/archive/20230316/202303160201.bnmM2caW-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Link: https://lore.kernel.org/r/202303160201.bnmM2caW-lkp@intel.com/

smatch warnings:
drivers/tty/serdev/serdev-ttyport.c:273 serdev_tty_port_register() warn: variable dereferenced before check 'drv' (see line 270)

vim +/drv +273 drivers/tty/serdev/serdev-ttyport.c

bed35c6dfa6a36 Rob Herring  2017-02-02  264  struct device *serdev_tty_port_register(struct tty_port *port,
bed35c6dfa6a36 Rob Herring  2017-02-02  265  					struct device *parent,
bed35c6dfa6a36 Rob Herring  2017-02-02  266  					struct tty_driver *drv, int idx)
bed35c6dfa6a36 Rob Herring  2017-02-02  267  {
bed35c6dfa6a36 Rob Herring  2017-02-02  268  	struct serdev_controller *ctrl;
bed35c6dfa6a36 Rob Herring  2017-02-02  269  	struct serport *serport;
225acc66b125b9 Sherry Sun   2023-03-15 @270  	dev_t devt = MKDEV(drv->major, drv->minor_start) + idx;
                                                                   ^^^^^       ^^^^^
Dereferences.

bed35c6dfa6a36 Rob Herring  2017-02-02  271  	int ret;
bed35c6dfa6a36 Rob Herring  2017-02-02  272  
bed35c6dfa6a36 Rob Herring  2017-02-02 @273  	if (!port || !drv || !parent)
                                                             ^^^^
Checked too late.  Are these checks really required?

bed35c6dfa6a36 Rob Herring  2017-02-02  274  		return ERR_PTR(-ENODEV);
bed35c6dfa6a36 Rob Herring  2017-02-02  275  
bed35c6dfa6a36 Rob Herring  2017-02-02  276  	ctrl = serdev_controller_alloc(parent, sizeof(struct serport));
bed35c6dfa6a36 Rob Herring  2017-02-02  277  	if (!ctrl)
bed35c6dfa6a36 Rob Herring  2017-02-02  278  		return ERR_PTR(-ENOMEM);
bed35c6dfa6a36 Rob Herring  2017-02-02  279  	serport = serdev_controller_get_drvdata(ctrl);
bed35c6dfa6a36 Rob Herring  2017-02-02  280  
bed35c6dfa6a36 Rob Herring  2017-02-02  281  	serport->port = port;
bed35c6dfa6a36 Rob Herring  2017-02-02  282  	serport->tty_idx = idx;
bed35c6dfa6a36 Rob Herring  2017-02-02  283  	serport->tty_drv = drv;
bed35c6dfa6a36 Rob Herring  2017-02-02  284  
225acc66b125b9 Sherry Sun   2023-03-15  285  	ctrl->dev.devt = devt;
bed35c6dfa6a36 Rob Herring  2017-02-02  286  	ctrl->ops = &ctrl_ops;
bed35c6dfa6a36 Rob Herring  2017-02-02  287  
aee5da7838787f Johan Hovold 2017-04-11  288  	port->client_ops = &client_ops;
aee5da7838787f Johan Hovold 2017-04-11  289  	port->client_data = ctrl;
aee5da7838787f Johan Hovold 2017-04-11  290  
bed35c6dfa6a36 Rob Herring  2017-02-02  291  	ret = serdev_controller_add(ctrl);
bed35c6dfa6a36 Rob Herring  2017-02-02  292  	if (ret)
aee5da7838787f Johan Hovold 2017-04-11  293  		goto err_reset_data;
bed35c6dfa6a36 Rob Herring  2017-02-02  294  
bed35c6dfa6a36 Rob Herring  2017-02-02  295  	dev_info(&ctrl->dev, "tty port %s%d registered\n", drv->name, idx);
bed35c6dfa6a36 Rob Herring  2017-02-02  296  	return &ctrl->dev;
bed35c6dfa6a36 Rob Herring  2017-02-02  297  
aee5da7838787f Johan Hovold 2017-04-11  298  err_reset_data:
aee5da7838787f Johan Hovold 2017-04-11  299  	port->client_data = NULL;
0c5aae59270fb1 Johan Hovold 2020-02-10  300  	port->client_ops = &tty_port_default_client_ops;
bed35c6dfa6a36 Rob Herring  2017-02-02  301  	serdev_controller_put(ctrl);
aee5da7838787f Johan Hovold 2017-04-11  302  
bed35c6dfa6a36 Rob Herring  2017-02-02  303  	return ERR_PTR(ret);
bed35c6dfa6a36 Rob Herring  2017-02-02  304  }

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests