linux-ext4 - Re: [PATCH 2/2] ext3: ext3

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Date:	Tue, 2 Oct 2012 11:27:23 -0300
From:	Carlos Maiolino <cmaiolino@...hat.com>
To:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] ext3: ext3_bread usage audit

Hi Jan
On Tue, Oct 02, 2012 at 03:55:13PM +0200, Jan Kara wrote:
> On Mon 01-10-12 16:50:55, Carlos Maiolino wrote:
> > This is the ext3 version of the same patch applied to Ext4, where such goal is
> > to audit the usage of ext3_bread() due a possible misinterpretion of its return
> > value.
> > 
> > Focused on directory blocks, a NULL value returned from ext3_bread() means a
> > hole, which cannot exist into a directory inode. It can pass undetected after a
> > fix in an uninitialized error variable.
> > 
> > The (now) initialized variable into ext3_getblk() may lead to a zero'ed return
> > value of ext3_bread() to its callers, which can make the caller do not detect
> > the hole in the directory inode.
> > 
> > This checks for directory holes when buffer_head and error value are both
> > zero'ed returning -EIO to their callers
> > 
> > Some ext3_bread() callers do not needed any changes either because they already
> > had its own hole detector paths or because these are deprecaded (like
> > dx_show_entries)
>   Umm, can you wrap the check for hole + error message in a helper function
> like ext3_dir_bread() please? That would save us quite some dupplication..
> Thanks!
>
I thought about a kind of handler too, but haven't done something like that by
Ted's suggestion. Please see thread
http://marc.info/?l=linux-ext4&m=134827512716575&w=2

But I can work on a kind of wrapper for ext3 if this is ok for you and send a V2
version of this patch.

Cheers,
Carlos  

-- 
--Carlos
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