linux-kernel - Re: Known and unfixed active data loss bug in MM + XFS with large folios since Dec 2021 (any kernel from 6.1 upwards)

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: <ZuuBs762OrOk58zQ@dread.disaster.area>
Date: Thu, 19 Sep 2024 11:43:15 +1000
From: Dave Chinner <david@...morbit.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: Chris Mason <clm@...a.com>, Jens Axboe <axboe@...nel.dk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Christian Theune <ct@...ingcircus.io>, linux-mm@...ck.org,
	"linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Daniel Dao <dqminh@...udflare.com>, regressions@...ts.linux.dev,
	regressions@...mhuis.info
Subject: Re: Known and unfixed active data loss bug in MM + XFS with large
 folios since Dec 2021 (any kernel from 6.1 upwards)

On Wed, Sep 18, 2024 at 02:34:57PM +0100, Matthew Wilcox wrote:
> On Wed, Sep 18, 2024 at 11:28:52AM +0200, Chris Mason wrote:
> > I think the bug was in __filemap_add_folio()'s usage of xarray_split_alloc()
> > and the tree changing before taking the lock.  It's just a guess, but that
> > was always my biggest suspect.
> 
> Oh god, that's it.
> 
> there should have been an xas_reset() after calling xas_split_alloc().
> 
> and 6758c1128ceb calls xas_reset() after calling xas_split_alloc().

Should we be asking for 6758c1128ceb to be backported to all
stable kernels then?

-Dave.
-- 
Dave Chinner
david@...morbit.com