linux-kernel - Re: Locking problem in overlayfs

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: <20141027141935.GC3021@tucsk.piliscsaba.szeredi.hu>
Date:	Mon, 27 Oct 2014 15:19:35 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	David Howells <dhowells@...hat.com>
Cc:	Al Viro <viro@...IV.linux.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-unionfs@...r.kernel.org
Subject: Re: Locking problem in overlayfs

On Mon, Oct 27, 2014 at 02:05:18PM +0000, David Howells wrote:
> Using my testsuite, I see the attached moan from lockdep.  Unfortunately, it
> doesn't cause the testsuite to actually fail, so I'm going to have to manually
> try and isolate the failing test.
> 
> David
> 
> =============================================
> [ INFO: possible recursive locking detected ]
> 3.18.0-rc2-fsdevel+ #910 Tainted: G        W     
> ---------------------------------------------
> run/2642 is trying to acquire lock:
>  (&sb->s_type->i_mutex_key#10/1){+.+.+.}, at: [<ffffffff81203d81>] ovl_cleanup_whiteouts+0x29/0xb4
> 
> but task is already holding lock:
>  (&sb->s_type->i_mutex_key#10/1){+.+.+.}, at: [<ffffffff8113abff>] lock_rename+0xb7/0xd7

Uh-oh.  We changed nesting late in the cycle and I didn't retest with lockdep.

And it's actually harmless, but AFAICS needs another level of nesting between
I_MUTEX_CHILD and I_MUTEX_NORMAL.

Will do a patch.

Thanks,
Miklos
--
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/