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    SubjectRe: [regression] nf_iterate(), BUG: unable to handle kernel NULL pointer dereference
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    On Thu, 2008-07-24 at 11:51 -0700, Andrew Morton wrote:
    > On Thu, 24 Jul 2008 16:34:36 +0300 Pekka Enberg <penberg@cs.helsinki.fi> wrote:
    >
    > > > >> Your patch introduced a use-after-free and double-free.
    > > > >> krealloc() frees the old pointer, but it is still used
    > > > >> for the ->move operations, then freed again.
    > > > >>
    > > > >> To fix this I think we need a __krealloc() that doesn't
    > > > >> free the old memory, especially since it must not be
    > > > >> freed immediately because it may still be used in a RCU
    > > > >> read side (see the last part in the patch attached to
    > > > >> this mail (based on a kernel without your patch)).
    > > > >
    > > > > Agreed. Something like this, perhaps?
    > > > >
    > > > > [PATCH] netfilter: fix double-free and use-after free
    > > > >
    > > > > As suggested by Patrick McHardy, introduce a __krealloc() that doesn't
    > > > > free the original buffer to fix a double-free and use-after-free bug
    > > > > introduced by me in netfilter that uses RCU.
    > > > >
    > > > > Reported-by: Patrick McHardy <kaber@trash.net>
    > > > > Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
    > > >
    > > > Looks good to me, thanks.
    > >
    > > Ingo, can you please test this? Andrew, I'm at OLS so can you pick up
    > > the patch in your tree?
    >
    > Sure. Or Patrick can do so and it can be merged via the net tree.
    >
    > Ingo, did this patch actually fix something over there?

    Apparently it didn't but it did fix Dieter's problem:

    http://lkml.org/lkml/2008/7/24/337

    Dieter, can we add a Tested-by tag from you to this patch?



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