linux-kernel - Re: [patch v2] fcntl: return -EFAULT if copy_to

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4C07AD0C.8090409@oss.ntt.co.jp>
Date:	Thu, 03 Jun 2010 22:24:28 +0900
From:	Takuya Yoshikawa <yoshikawa.takuya@....ntt.co.jp>
To:	Nick Piggin <npiggin@...e.de>
CC:	Eric Dumazet <eric.dumazet@...il.com>,
	Jens Axboe <jaxboe@...ionio.com>,
	Dan Carpenter <error27@...il.com>,
	Matthew Wilcox <matthew@....cx>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [patch v2] fcntl: return -EFAULT if copy_to_user fails

(2010/06/03 22:10), Nick Piggin wrote:
> On Thu, Jun 03, 2010 at 02:38:03PM +0200, Eric Dumazet wrote:
>> Le jeudi 03 juin 2010 à 21:16 +0900, Takuya Yoshikawa a écrit :
>>> (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 = 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?
>>>
>>> IIUC, from the beginning, when these were introduced.
>>
>> Maybe copy_to_user() was changed sometime to return a partial count
>> instead of EFAULT ?
>
> I think it's been like that since first introduced. Some functions
> do need to know in order to do partial copies.
>
>
>> 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 = copy_to_user(arg1, arg2, arg3);
>>
>> 	return (res>  0) ? -EFAULT : res;
>> }
>
> It would be unfortunate if it adds more confusion. I'd prefer to have
> a sufficiently different name. memcpy_to_user/memcpy_from_user
> perhaps?

Then, and memclear_user() ?

>

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/