From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gmZgz-00042d-5J for barebox@lists.infradead.org; Thu, 24 Jan 2019 07:44:54 +0000 Date: Thu, 24 Jan 2019 08:44:50 +0100 From: Sascha Hauer Message-ID: <20190124074450.f3wykwn42qqqcfrz@pengutronix.de> References: <20190123011338.32517-1-andrew.smirnov@gmail.com> <20190123011338.32517-5-andrew.smirnov@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190123011338.32517-5-andrew.smirnov@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH 4/7] fs: Change error checking logic for fsdrv->lseek() call To: Andrey Smirnov Cc: barebox@lists.infradead.org On Tue, Jan 22, 2019 at 05:13:35PM -0800, Andrey Smirnov wrote: > On 32-bit systems, cheking for IS_ERR_VALUE(pos) is not > correct. Expanding that code we get (loff_t cast is added for clarity): > > (loff_t)pos >= (unsigned long)-MAX_ERRNO > > given that loff_t is a 64-bit signed value, any perfectly valid seek > offset that is greater than 0xffffc000 will result in false > positive. Change the logic to check if position returned by > fsdrv->lseek() is what's been requested. If it is, we can assume that > operation was succesfull. If not, that's likely means failure and > return value is a negative error code. > > This should accomodate both 32-bit systems, where we /dev/mem doesn't > present any range problems, as well as 64-bit systems where both file > offset and size of /dev/mem couldn't really be correctly captured by > loff_t and we have to rely on 2's complement and overflow. > > Signed-off-by: Andrey Smirnov > --- > fs/fs.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/fs/fs.c b/fs/fs.c > index a304bf186..6a62fb98b 100644 > --- a/fs/fs.c > +++ b/fs/fs.c > @@ -405,8 +405,7 @@ loff_t lseek(int fildes, loff_t offset, int whence) > { > struct fs_driver_d *fsdrv; > FILE *f; > - loff_t pos; > - int ret; > + loff_t pos, ret; > > if (check_fd(fildes)) > return -1; > @@ -442,13 +441,11 @@ loff_t lseek(int fildes, loff_t offset, int whence) > goto out; > } > > - pos = fsdrv->lseek(&f->fsdev->dev, f, pos); > - if (IS_ERR_VALUE(pos)) { > - errno = -pos; > - return -1; > - } > + ret = fsdrv->lseek(&f->fsdev->dev, f, pos); > + if (ret != pos) > + goto out; There's no point in returning the current position from fsdrv->lseek when the desired position is already an input parameter. I think we should change the prototype of fsdrv->lseek to just return an error code. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox