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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Jeff Liu <jeff.liu@oracle.com>
Cc: xfs@oss.sgi.com
Subject: Re: potential use after free in xfs_iomap_write_allocate()
Date: Mon, 10 Feb 2014 17:50:41 +0300	[thread overview]
Message-ID: <20140210145041.GC26776@mwanda> (raw)
In-Reply-To: <52F8E086.8030805@oracle.com>

On Mon, Feb 10, 2014 at 10:21:58PM +0800, Jeff Liu wrote:
> 
> On 02/10 2014 18:36 PM, Dan Carpenter wrote:
> > There is a static checker warning in xfs_iomap_write_allocate().  It's
> > sort of old so probably it's a false positive.
> > 
> > 	fs/xfs/xfs_iomap.c:798 xfs_iomap_write_allocate()
> > 	warn: 'tp' was already freed.
> > 
> > fs/xfs/xfs_iomap.c
> >    677  
> >    678          while (count_fsb != 0) {
> > 
> > There are some paths where if (count_fsb == 0) then "tp" is free.
> 
> I can not see a call pach would introduce "count_fsb == 0" because we only
> call xfs_iomap_write_allocate() in extent delayed allocation context,
> that is the count_fsb should be >= 1.

I am confused.  That's a while condition and not an if condition.
On line 792 we do:

	count_fsb -= imap->br_blockcount;

I assume you saw that, and it's still a false positive but I just want
to be sure.

regards,
dan carpenter

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  reply	other threads:[~2014-02-10 14:50 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-10 10:36 potential use after free in xfs_iomap_write_allocate() Dan Carpenter
2014-02-10 14:21 ` Jeff Liu
2014-02-10 14:50   ` Dan Carpenter [this message]
2014-02-10 21:34   ` Dave Chinner

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