linux-ext4 - Re: [PATCH] ext4: fix NULL pointer dereference in ext4_quota

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Message-ID: <20110516101329.GC5344@quack.suse.cz>
Date:	Mon, 16 May 2011 12:13:29 +0200
From:	Jan Kara <jack@...e.cz>
To:	Lukas Czerner <lczerner@...hat.com>
Cc:	Amir Goldstein <amir73il@...il.com>,
	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	Theodore Tso <tytso@....edu>, Jan Kara <jack@...e.cz>
Subject: Re: [PATCH] ext4: fix NULL pointer dereference in ext4_quota_off

On Mon 16-05-11 11:49:22, Lukas Czerner wrote:
> On Mon, 16 May 2011, Amir Goldstein wrote:
> > diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> > index fc827bb..2689351 100644
> > --- a/fs/ext4/super.c
> > +++ b/fs/ext4/super.c
> > @@ -4681,6 +4681,9 @@ static int ext4_quota_off(struct super_block
> > *sb, int type)
> >  	if (test_opt(sb, DELALLOC))
> >  		sync_filesystem(sb);
> > 
> > +	if (!inode)
> > +		goto out;
> 
> Just out of curiosity, why would the quota inode be NULL ?
  Because quota is already turned off (we then release all references to
quota file). Just what I don't understand is why in Amir's testing quota is
not turned on before calling quota off. Because when I run the same test, I
don't trigger the issue.

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