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Subject: Re: ubifs: error unwinding trouble
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Adrian Hunter <adrian.hunter@nokia.com>
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Date: Fri, 24 Jul 2009 15:17:46 +0300
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Cc: "Bityutskiy Artem \(Nokia-M/Helsinki\)" <Artem.Bityutskiy@nokia.com>,
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	Daniel Mack <daniel@caiaq.de>, Adrian Hunter <ext-adrian.hunter@nokia.com>
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On Fri, 2009-07-24 at 13:49 +0300, Adrian Hunter wrote:
> Daniel Mack wrote:
> > On a recent git kernel, the error unwinding for UBIFS seems to have some
> > problem, most probably a double-free or something similar.
> > 
> > When UBI is pointed to the right mtd partition (using command line
> > arguments) , everything is fine. But when it's (accidentionally) set to
> > some very small mtd, the attach process fails. Which wouldn't be a bad
> > thing by itself, but it somehow messes up the slub/slab allocators then
> > which causes very strange memory corruption effects - see the backtrace
> > below.
> > 
> > The Ooops itself is unreleated to UBI, but it does not occur when UBI
> > succeeds in attaching the volume.
> > 
> > Any idea? I searched for awhile but couldn't see anything obvious.
> 
> Looks like a double free of the eba_tbl
> 
> This might help:
> 
> diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
> index 0f2034c..e4d9ef0 100644
> --- a/drivers/mtd/ubi/eba.c
> +++ b/drivers/mtd/ubi/eba.c
> @@ -1254,6 +1254,7 @@ out_free:
>                 if (!ubi->volumes[i])
>                         continue;
>                 kfree(ubi->volumes[i]->eba_tbl);
> +               ubi->volumes[i]->eba_tbl = NULL;
>         }
>         return err;
>  }

You are right. I've just pushed your patch to ubi-2.6.git/master.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)