From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [patch v2] fcntl: return -EFAULT if copy_to_user fails
Date: Thu, 03 Jun 2010 14:38:03 +0200
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	 <20100603103542.GV5483@bicker> <4C07990A.8080508@fusionio.com>
	 <4C079D34.5010500@oss.ntt.co.jp>
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Cc: Jens Axboe <jaxboe@fusionio.com>,
	Dan Carpenter <error27@gmail.com>,
	Matthew Wilcox <matthew@wil.cx>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
To: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
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Le jeudi 03 juin 2010 =C3=A0 21:16 +0900, Takuya Yoshikawa a =C3=A9crit=
 :
> (2010/06/03 20:59), Jens Axboe wrote:
> > On 2010-06-03 12:35, Dan Carpenter wrote:
> >> copy_to_user() returns the number of bytes remaining, but we want =
to
> >> return -EFAULT.
> >> 	ret =3D fcntl(fd, F_SETOWN_EX, NULL);
> >> With the original code ret would be 8 here.
> >>
> >> V2: Takuya Yoshikawa pointed out a similar issue in f_getown_ex()
> >
> > Pretty basic bug, how long has this been there?
>=20
> IIUC, from the beginning, when these were introduced.

Maybe copy_to_user() was changed sometime to return a partial count
instead of EFAULT ?

I do think we should have a set of helper functions, instead of
spreading special EFAULT cases in one housand places...

This is really ugly.

static inline int sec_copy_to_user(arg1, arg2, arg3)
{
	int res =3D copy_to_user(arg1, arg2, arg3);

	return (res > 0) ? -EFAULT : res;
}