linux-ext4 - Re: ext2/ext3 different block_sizes/i

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]

Date:	Thu, 25 Mar 2010 02:18:12 +0300
From:	Evgeniy Ivanov <lolkaantimat@...il.com>
To:	linux-ext4@...r.kernel.org
Subject: Re: ext2/ext3 different block_sizes/i_size/e2fsck question

I've also noted a very interesting and strange thing. I checked a file
for which e2fsck did 67445000->67446784 i_size change.
debugfs stat comparison between fixed file and file with old size
differs in i_size *only* (all blocks are the same), but cmp shows
difference in 67382273 (it's constant for any bogus file), that is
block 65803 which is the last before triple indirection. How did file
change if e2fsck just had changed i_size and both values are greater
than 67382273?


On Wed, Mar 24, 2010 at 10:27 PM, Evgeniy Ivanov <lolkaantimat@...il.com> wrote:
> Hello,
>
> Sorry for bothering list with my ext2 questions.
> I got into trouble with my ext2 implementation and filesystem with
> 1024 block size. Sometimes when I write files they're written
> correctly (md5sum is the same as original, i_size is correct either),
> but e2fsck changes i_size to another values (which breaks files). E.g.
> 67445000->67446784 or 67445248->67446784. I see that new sizes are
> numbers of multiples of 1024.
> Strange thing is that I can't reproduce this problem with 2048 and
> 4096 block sizes. I thought the problem was in trash in unused part of
> last block (actually it is zeroed), but then it would be reproduceable
> in fs with another block size.
> How does ext2 decide to fix that files sizes? Any suggestions?
>
> Thanks in advance for any help.
>
>
> --
> Evgeniy Ivanov
>



-- 
Evgeniy Ivanov
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html