linux-ext4 - Re: [Suggestion] fs/ext3: memory leak by calling set_qf_name or clear_qf

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Message-ID: <20130107195425.GE13659@quack.suse.cz>
Date:	Mon, 7 Jan 2013 20:54:25 +0100
From:	Jan Kara <jack@...e.cz>
To:	Chen Gang <gang.chen@...anux.com>
Cc:	Jan Kara <jack@...e.cz>, Theodore Ts'o <tytso@....edu>,
	akpm@...ux-foundation.org, linux-ext4@...r.kernel.org
Subject: Re: [Suggestion] fs/ext3: memory leak by calling set_qf_name or
 clear_qf_name, many times.

On Fri 04-01-13 13:39:37, Chen Gang wrote:
> 于 2012年12月31日 20:06, Jan Kara 写道:
> >   Thanks for report. Yes, memory leak seems to be possible. Attached patch
> > should fix it, I have added it to my tree.
> > 
> > 									Honza
> > 
> 
>   after read your patch, today (although I am not a reviewer).
>   is it a possible situation like this (just my imagination):
>     1st let it call clear_qf_name successfully.
>     2nd let it call set_qf_name successfully.
>     3rd call clear_qf_name again ?
  Although this is not likely in practice, if you specify mount options
like usrjquota=aquota.user,usrjquota=,usrjquota=aquota.user it can happen.
Thanks for spotting this.

>     ...
>   if this situation is possible.
>     I guess the memory still leak, after apply your patch.
> 
>   if what I guess is true
>     it seems we have to duplicate memory for old_opts in ext3_remount.
>     and for clear_qf_name, set_qf_name, ext3_remount:
>       use normal memory allocation and free ways instead of current using.
  Yes. Updated patch attached.

									Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR

View attachment "0001-ext3-Fix-memory-leak-when-quota-options-are-specifie.patch" of type "text/x-patch" (3347 bytes)