Re: [PATCH] ext3: htree entry integrity checking

Re: [PATCH] ext3: htree entry integrity checking

[Andreas Dilger]

On Nov 16, 2006  11:50 -0500, Jeff Mahoney wrote:
>  Currently, if a corrupted directory entry with rec_len=0 is encountered,
>  we still trust that the data is valid. This can cause an infinite loop
>  in htree_dirblock_to_tree() since the iteration loop will never make any
>  progress.

Actually, I think Eric Sandeen was working on similar fixes already, and
instead of doing a per-item check each time we look at the entry it does
a full-block check the first time it is read (as ext2 does).

>  This fixes the problem described at:
>  http://projects.info-pull.com/mokb/MOKB-10-11-2006.html

Would also be good to CC linux-ext4, where the ext3 maintainers live.
Hmm, maybe we need to update MAINTAINERS with the new list address?

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

Re: [PATCH] ext3: htree entry integrity checking

[Eric Sandeen]

Andreas Dilger wrote:
> On Nov 16, 2006  11:50 -0500, Jeff Mahoney wrote:
>>  Currently, if a corrupted directory entry with rec_len=0 is encountered,
>>  we still trust that the data is valid. This can cause an infinite loop
>>  in htree_dirblock_to_tree() since the iteration loop will never make any
>>  progress.
> 
> Actually, I think Eric Sandeen was working on similar fixes already, and
> instead of doing a per-item check each time we look at the entry it does
> a full-block check the first time it is read (as ext2 does).
> 
>>  This fixes the problem described at:
>>  http://projects.info-pull.com/mokb/MOKB-10-11-2006.html
> 
> Would also be good to CC linux-ext4, where the ext3 maintainers live.
> Hmm, maybe we need to update MAINTAINERS with the new list address?

This should already be fixed, in some fashion, in -mm:

http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.19-rc5/2.6.19-rc5-mm2/broken-out/handle-ext3-directory-corruption-better.patch

I have been looking at doing a check only when the block is first read,
but other things have come up & taken some time, and that is a bit on
the back burner now...

-Eric

Re: [PATCH] ext3: htree entry integrity checking

[Jeff Mahoney]

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Andreas Dilger wrote:
> On Nov 16, 2006  11:50 -0500, Jeff Mahoney wrote:
>>  Currently, if a corrupted directory entry with rec_len=0 is encountered,
>>  we still trust that the data is valid. This can cause an infinite loop
>>  in htree_dirblock_to_tree() since the iteration loop will never make any
>>  progress.
> 
> Actually, I think Eric Sandeen was working on similar fixes already, and
> instead of doing a per-item check each time we look at the entry it does
> a full-block check the first time it is read (as ext2 does).
> 
>>  This fixes the problem described at:
>>  http://projects.info-pull.com/mokb/MOKB-10-11-2006.html
> 
> Would also be good to CC linux-ext4, where the ext3 maintainers live.

Ok, thanks. If that's already in -mm, I'll use that one.

- -Jeff

- --
Jeff Mahoney
SUSE Labs
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