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From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 2/5] repair: fix some valgrind reported errors on i686
Date: Mon, 10 Oct 2011 11:20:17 +1100	[thread overview]
Message-ID: <20111010002017.GQ3159@dastard> (raw)
In-Reply-To: <20111009234529.GA13527@infradead.org>

On Sun, Oct 09, 2011 at 07:45:29PM -0400, Christoph Hellwig wrote:
> On Mon, Oct 10, 2011 at 10:11:47AM +1100, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > Fix a potential prefetch read problem due to the first loop
> > execution of pf_batch_read potentially not initialising the fsbno
> > varaible:
> 
> variable.
> 
> > 
> > ==10177== Thread 6:
> > ==10177== Conditional jump or move depends on uninitialised value(s)
> > ==10177==    at 0x8079CAB: pf_batch_read (prefetch.c:408)
> > ==10177==    by 0x6A2996D: clone (clone.S:130)
> > ==10177==
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> >  repair/prefetch.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/repair/prefetch.c b/repair/prefetch.c
> > index d2fdf90..da074a8 100644
> > --- a/repair/prefetch.c
> > +++ b/repair/prefetch.c
> > @@ -397,7 +397,7 @@ pf_batch_read(
> >  	int			len, size;
> >  	int			i;
> >  	int			inode_bufs;
> > -	unsigned long		fsbno;
> > +	unsigned long		fsbno = 0;
> 
> Call me stupid, but I can't see how this could actually be a real
> life issue.  The first thing we do in the loop is to to write
> to fsbno in btree_find.  I'm fine adding this to shut up warnins,
> but I can't see a real issue.

If btree_find() fails to find the key being looked up, it returns
without having initialised fsbno.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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  reply	other threads:[~2011-10-10  0:20 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-09 23:11 [PATCH 0/5, v2] repair: sector size and blkmap fixes Dave Chinner
2011-10-09 23:11 ` [PATCH 1/5] repair: handle repair of image files on large sector size filesystems Dave Chinner
2011-10-09 23:52   ` Christoph Hellwig
2011-10-10  0:17     ` Dave Chinner
2011-10-10  0:19       ` Christoph Hellwig
2011-10-09 23:11 ` [PATCH 2/5] repair: fix some valgrind reported errors on i686 Dave Chinner
2011-10-09 23:45   ` Christoph Hellwig
2011-10-10  0:20     ` Dave Chinner [this message]
2011-10-10 13:14       ` Christoph Hellwig
2011-10-09 23:11 ` [PATCH 3/5] repair: handle memory allocation failure from blkmap_grow Dave Chinner
2011-10-09 23:51   ` Christoph Hellwig
2011-10-10  0:10     ` Dave Chinner
2011-10-09 23:11 ` [PATCH 4/5] repair: don't cache large blkmap allocations Dave Chinner
2011-10-09 23:48   ` Christoph Hellwig
2011-10-10  0:14     ` Dave Chinner
2011-10-10 13:22       ` Christoph Hellwig
2011-10-09 23:11 ` [PATCH 5/5] repair: prevent blkmap extent count overflows Dave Chinner

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