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Wed, 01 Aug 2018 16:03:56 -0700 (PDT) Date: Wed, 1 Aug 2018 16:03:54 -0700 From: Dmitry Torokhov To: Julia Lawall Cc: joe@perches.com, Chengguang Xu , kernel-janitors@vger.kernel.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] Input: elan_i2c_smbus - cast sizeof to int for comparison Message-ID: <20180801230354.GA184797@dtor-ws> References: <1530466325-1678-1-git-send-email-Julia.Lawall@lip6.fr> <1530466325-1678-2-git-send-email-Julia.Lawall@lip6.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1530466325-1678-2-git-send-email-Julia.Lawall@lip6.fr> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 01, 2018 at 07:32:03PM +0200, Julia Lawall wrote: > Comparing an int to a size, which is unsigned, causes the int to become > unsigned, giving the wrong result. i2c_smbus_read_block_data can return the > result of i2c_smbus_xfer, whih can return a negative error code. > > A simplified version of the semantic match that finds this problem is as > follows: (http://coccinelle.lip6.fr/) > > // > @@ > int x; > expression e,e1; > identifier f; > @@ > > *x = f(...); > ... when != x = e1 > when != if (x < 0 || ...) { ... return ...; } > *x < sizeof(e) > // > > Signed-off-by: Julia Lawall > Applied, thank you. > --- > drivers/input/mouse/elan_i2c_smbus.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/input/mouse/elan_i2c_smbus.c b/drivers/input/mouse/elan_i2c_smbus.c > index c060d27..88e315d 100644 > --- a/drivers/input/mouse/elan_i2c_smbus.c > +++ b/drivers/input/mouse/elan_i2c_smbus.c > @@ -387,7 +387,7 @@ static int elan_smbus_prepare_fw_update(struct i2c_client *client) > len = i2c_smbus_read_block_data(client, > ETP_SMBUS_IAP_PASSWORD_READ, > val); > - if (len < sizeof(u16)) { > + if (len < (int)sizeof(u16)) { > error = len < 0 ? len : -EIO; > dev_err(dev, "failed to read iap password: %d\n", > error); > -- Dmitry