linux-ext4 - Re: [PATCH 2/5] ext2: code cleanup by calling ext2_group_last_block

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <16e45402a18.c7fb3dc01505.2507377017571315195@mykernel.net>
Date:   Thu, 07 Nov 2019 17:44:23 +0800
From:   Chengguang Xu <cgxu519@...ernel.net>
To:     "Jan Kara" <jack@...e.cz>
Cc:     "jack" <jack@...e.com>, "linux-ext4" <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 2/5] ext2: code cleanup by calling
 ext2_group_last_block_no()

 ---- 在 星期四, 2019-11-07 17:21:17 Jan Kara <jack@...e.cz> 撰写 ----
 > On Thu 07-11-19 10:54:43, Chengguang Xu wrote:
 > >  ---- 在 星期三, 2019-11-06 23:42:36 Jan Kara <jack@...e.cz> 撰写 ----
 > >  > On Mon 04-11-19 19:40:33, Chengguang Xu wrote:
 > >  > > Call common helper ext2_group_last_block_no() to
 > >  > > calculate group last block number.
 > >  > > 
 > >  > > Signed-off-by: Chengguang Xu <cgxu519@...ernel.net>
 > >  > 
 > >  > Thanks for the patch! I've applied it (as well as 1/5) and added attached
 > >  > simplification on top.
 > >  > 
 > > 
 > > In ext2_try_to_allocate()
 > > 
 > > +        if (my_rsv->_rsv_end < group_last_block)
 > > +            end = my_rsv->_rsv_end - group_first_block + 1;
 > > +        if (grp_goal < start || grp_goal > end)
 > > 
 > > Based on original code, shouldn't it be  if (grp_goal < start || grp_goal
 > > >=end) ?
 > 
 > Hum, that's a good point. The original code actually had an off-by-one bug
 > because 'end' is really the last block that can be used so grp_goal == end
 > still makes sense. And my cleanup fixed it. Now looking at the code in
 > ext2_try_to_allocate() we also have a similar bug in the loop allocating
 > blocks. There we can also go upto 'end' inclusive. Added a patch to fix
 > that. Thanks for pointing me to this!
 > 

Doesn't it depend on what starting number for grp_block inside block group?
if it starts from 0, is the end number block still available for allocation?

Thanks,
Chengguang