From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
To: Masayuki Ohtake <masa-korg-ECg8zkTtlr0C6LszWs/t0g@public.gmane.org>
Cc: andrew.chih.howe.khor-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
joel.clark-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, "Wang,
Yong Y" <yong.y.wang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
qi.wang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
"Ben Dooks (embedded platforms)"
<ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>,
"Jean Delvare (PC drivers,
core)" <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Subject: Re: [PATCH] I2C driver of Topcliff PCH
Date: Tue, 20 Jul 2010 11:29:52 +0200 [thread overview]
Message-ID: <201007201129.53110.arnd@arndb.de> (raw)
In-Reply-To: <000601cb27e4$3768c170$66f8800a-a06+6cuVnkTSQfdrb5gaxUEOCMrvLtNR@public.gmane.org>
On Tuesday 20 July 2010, Masayuki Ohtake wrote:
> > > @@ -147,6 +148,11 @@ static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
> > > if (tmp == NULL)
> > > return -ENOMEM;
> > >
> > > + if (copy_from_user(tmp, buf, count)) {
> > > + kfree(tmp);
> > > + return -EFAULT;
> > > + }
> > > +
> > > pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
> > > iminor(file->f_path.dentry->d_inode), count);
> >
> >
> > A read function should not do copy_from_user, only copy_to_user.
> > If you are worried about returning invalid data from kernel space,
> > better use kzalloc instead of kmalloc to get the buffer.
>
> Our I2C HW has special mode.
> To control the mode, our i2c driver has copy_from_user.
That is a highly unusual interface and I would definitely not recommend doing
this. Please use an ioctl operation for anything that has both input and output
data.
Arnd
next prev parent reply other threads:[~2010-07-20 9:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4C204B0D.2030201@dsn.okisemi.com>
2010-07-15 7:42 ` [PATCH] I2C driver of Topcliff PCH Masayuki Ohtak
[not found] ` <4C3EBBEC.9020304-ECg8zkTtlr0C6LszWs/t0g@public.gmane.org>
2010-07-15 19:35 ` Arnd Bergmann
2010-07-20 0:05 ` Masayuki Ohtake
2010-07-20 4:55 ` Masayuki Ohtake
[not found] ` <000401cb27c7$ce732960$66f8800a-a06+6cuVnkTSQfdrb5gaxUEOCMrvLtNR@public.gmane.org>
2010-07-20 9:27 ` Arnd Bergmann
2010-07-20 12:38 ` Masayuki Ohtake
2010-07-20 8:19 ` Masayuki Ohtake
[not found] ` <000601cb27e4$3768c170$66f8800a-a06+6cuVnkTSQfdrb5gaxUEOCMrvLtNR@public.gmane.org>
2010-07-20 9:29 ` Arnd Bergmann [this message]
2010-07-20 12:40 ` Masayuki Ohtake
[not found] ` <4C204B0D.2030201-ECg8zkTtlr0C6LszWs/t0g@public.gmane.org>
2010-07-21 6:46 ` Masayuki Ohtak
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