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

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Message-ID: <20121004135746.GA3296@andromeda.usersys.redhat.com>
Date:	Thu, 4 Oct 2012 10:57:46 -0300
From:	Carlos Maiolino <cmaiolino@...hat.com>
To:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] ext3: ext3_bread usage audit [V2]

On Thu, Oct 04, 2012 at 03:02:44PM +0200, Jan Kara wrote:
> On Thu 04-10-12 14:42:12, Jan Kara wrote:
> > On Tue 02-10-12 23:59:23, 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)
> > > 
> > > V2: It adds a wrapper function ext3_dir_bread() to check for directory holes
> > > when reading blocks for a directory inode, and callers of ext3_bread() to read
> > > directory blocks were replaced by this wrapper.
> > > 
> > > Signed-off-by: Carlos Maiolino <cmaiolino@...hat.com>
> >   Oh, I see you already sent V2. Thanks. I've put the patch to my tree.
>   Umm, after checking - any reason why you didn't convert also ext3_bread()
> in dir.c and ext3_bread() in ext3_rename()?
> 
I didn't convert some calls for ext3_bread() - like ext3_readdir() - because
those really don't care about the err value, only about if bh is valid or not. I
can change this if you want, not a problem from my point.

-- 
--Carlos
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