[CentOS] Is ext4 safe for a production server?

James Hogarth james.hogarth at gmail.com
Fri Dec 11 09:39:39 UTC 2009


Best advisory link I've found:

http://www.vupen.com/english/advisories/2009/3468

2009/12/11 James Hogarth <james.hogarth at gmail.com>

> On that today perhaps those thinking of ext4 for production systems -
> especially shared multiuser systems - should check out CVE-2009-4131 ...
>
> CVE-2009-4131: Arbitrary file overwrite in ext4
>
> Insufficient permission checking in the ext4 filesytem could be
> exploited by local users to overwrite arbitrary files.
>
> Ksplice update ID: mfm62pmh
>
> 2009/12/11 Ross Walker <rswwalker at gmail.com>
>
> On Dec 10, 2009, at 7:52 PM, Mark Caudill <markca at codelulz.com> wrote:
>>
>> > Christopher Chan wrote:
>> >> Morten Torstensen wrote:
>> >>> On 08.12.2009 13:34, Chan Chung Hang Christopher wrote:
>> >>>>> Speaking for me (on Linux systems) on top of LVM on top of md.
>> >>>>> On IRIX
>> >>>>> as it was intended.
>> >>>>>
>> >>>> That is a disaster combination for XFS even now. You mentioned some
>> >>>> pretty hefty hardware in your other post...
>> >>> If XFS doesn't play well with LVM, how can it even be an option? I
>> >>> couldn't live without LVM...
>> >>>
>> >>
>> >> I meant it in the sense of data guarantee. XFS has a major history of
>> >> losing data unless used with hardware raid cards that have a bbu
>> >> cache.
>> >> That changed when XFS got barrier support.
>> >>
>> >> However, anything on LVM be it ext3, ext4 or XFS that has barrier
>> >> support will not be able to use barriers because device-mapper does
>> >> not
>> >> support barriers and therefore, if you use LVM, it better be on a
>> >> hardware raid array where the card has bbu cache.
>> >
>> > Wait, just to be clear, are you saying that all use of LVM is a bad
>> > idea
>> > unless on hardware RAID? That's bad it if it's true since it seems
>> > to me
>> > that most modern distros like to use LVM by default. Am I missing
>> > something?
>>
>> If you use a leading edge distro then they will most likely be using a
>> LVM version with barrier support as it was implemented as of
>> 2.6.29-2.6.30+.
>>
>> It should be backported by the next release of CentOS hopefully.
>>
>> -Ross
>>
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>>
>
>
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