linux-kernel - Re: 2.6.19 file content corruption on ext3

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: <Pine.LNX.4.64.0612181114160.3479@woody.osdl.org>
Date:	Mon, 18 Dec 2006 11:18:13 -0800 (PST)
From:	Linus Torvalds <torvalds@...l.org>
To:	Andrei Popa <andrei.popa@...eo.ro>
cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hugh@...itas.com>,
	Florian Weimer <fw@...eb.enyo.de>,
	Marc Haber <mh+linux-kernel@...schlus.de>,
	Martin Michlmayr <tbm@...ius.com>
Subject: Re: 2.6.19 file content corruption on ext3



On Mon, 18 Dec 2006, Andrei Popa wrote:
> 
> I applied Linus patch, Andrew patch, Peter Zijlstra patches(the last
> two). All unified patch is attached. I tested and I have no corruption.

That wasn't very interesting, because you also had the patch that just 
disabled "page_mkclean_one()" entirely:

> diff --git a/mm/rmap.c b/mm/rmap.c
> index d8a842a..3f9061e 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -448,7 +448,7 @@ static int page_mkclean_one(struct page 
>  		goto unlock;
>  
>  	entry = ptep_get_and_clear(mm, address, pte);
> -	entry = pte_mkclean(entry);
> +	/*entry = pte_mkclean(entry);*/
>  	entry = pte_wrprotect(entry);
>  	ptep_establish(vma, address, pte, entry);
>  	lazy_mmu_prot_update(entry);

The above patch is bad. It's always going to hide the bug, but it hides it 
by just not doing anything at all. So any patch combination that contains 
that patch will probably _always_ fix your problem, but it won't be an 
interesting patch..

So can you remove that small fragment? Also, it would be nice if you added 
the WARN_ON() to this sequence in mm/page-writeback.c:

+                       if (!must_clean_ptes && cleaned)
+                               set_page_dirty(page);

just make it do a WARN_ON() if this ever triggers.

Then, IF the corruption is gone, we'd love to see the WARN_ON results..

		Linus
-
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/