lkml.org 
[lkml]   [2012]   [Jul]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] fat: Support fallocate on fat.
Date
Namjae Jeon <linkinjeon@gmail.com> writes:

>>> + /*
>>> + * calculate i_blocks and mmu_private from the actual number of
>>> + * allocated clusters instead of doing it from file size.This ensures
>>> + * that the preallocated disk space using FALLOC_FL_KEEP_SIZE is
>>> + * persistent across remounts and writes go into the allocated
>>> clusters.
>>> + */
>>> + fat_calc_dir_size(inode);
>>
>> Looks like the wrong. If you didn't initialize preallocated space, the
>> data never be exposed to userland. It is security bug.
> As explained above, if we do append write instead of seeking into a
> random offset, there is no security risk.

So it means? - if we didn't, there is.

> The main disadvantage with initializing the preallocated space (as is
> done in case of without FALLOC_FL_KEEP_SIZE ) is it takes long time
> for bigger allocation sizes. It took ~70 seconds to preallocate 2GB on
> our target if FALLOC_FL_KEEP_SIZE is not set.

It doesn't become the reason to expose uninitialized data.

Thanks.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>


\
 
 \ /
  Last update: 2012-07-09 13:41    [W:0.098 / U:0.000 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site