linux-kernel - Re: [PATCH 5/5] fat: add mutex lock to fat_build

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] [day] [month] [year] [list]

Date:	Wed, 31 Oct 2012 09:46:49 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Ravishankar N <ravi.n1@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH 5/5] fat: add mutex lock to fat_build_inode

Namjae Jeon <linkinjeon@...il.com> writes:

> 2012/10/30, Andrew Morton <akpm@...ux-foundation.org>:
>> On Sun, 28 Oct 2012 10:53:43 +0900
>> Namjae Jeon <linkinjeon@...il.com> wrote:
>>
>>> From: Namjae Jeon <namjae.jeon@...sung.com>
>>>
>>> fat_nfs_get_inode does not hold i_mutex of parent directory.So add
>>> lock to fat_build_inode.
>>
> Hi. Andrew.
>> Well..  why?  Presumably this patch fixes some race.  A good
>> description of that race would be useful - partly because others may
>> then be able to suggest alternative ways of fixing that bug.
> We are making use of fat_build_inode to build the inode using 'i_pos'.
> Since, this function is local to FAT and when mounted over NFS. We can
> make use of FAT parallely from local NFS Server and mounted from NFS
> client. So, in order to avoid race to multiple regeneration for the
> same 'i_pos' - we have introduced this locking.

This lock fixes the NFS patches. FAT inode is embedded into
directory. So usual local ->lookup path is exclusive by
inode->i_mutex. But NFS patches (current -mm, IIRC) introduce the new
path for FH => inode lookup.

So, this lock is introduced.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
--
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/