linux-ext4 - Re: [PATCH] ext4: fix signed vs unsigned comparison in ext4_valid

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Message-ID: <20191023194605.GA7630@mit.edu>
Date:   Wed, 23 Oct 2019 15:46:05 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: fix signed vs unsigned comparison in
 ext4_valid_extent()

On Wed, Oct 23, 2019 at 11:43:33AM -0700, Ira Weiny wrote:
> On Wed, Oct 23, 2019 at 09:15:46AM -0400, Theodore Y. Ts'o wrote:
> > On Tue, Oct 22, 2019 at 10:44:47PM -0700, Eric Biggers wrote:
> > > 
> > > This patch can't be fixing anything because the comparison is unsigned both
> > > before and after this patch.
> > 
> > Thanks, you're right; I had forgotten C's signed/unsigned rules for
> > addition.  The funny thing is the original reporter of BZ #205197
> > reported that the problem went away he tried a similar patch.
> 
> Not trying to stick my nose in too much here but:
> 
> What does it mean if ext4_ext_get_actual_len() to return < 0?

It's not possible for it to return < 0.  We probably should clean it
up to make it return an unsigned int, but that's a longer-term clean-up.

      	      	     		 - Ted