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    SubjectRe: [PATCH] Ceph: Fix use-after-free bug in ceph_messenger_destroy()
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    On Sat, Dec 25, 2010 at 7:11 PM, Jesper Juhl <jj@chaosbits.net> wrote:
    > Hi,
    >
    > In net/ceph/messenger.c::ceph_messenger_destroy() the pointer 'msgr' is
    > freed by kfree() and subsequently used in a call to dout() - use after
    > free bug.

    As I sad before, %p reads only the address.

    > Easily fixed by simply moving the kfree() call after the dout() call.
    >
    > Signed-off-by: Jesper Juhl <jj@chaosbits.net>
    > ---
    >  messenger.c |    2 +-
    >  1 file changed, 1 insertion(+), 1 deletion(-)
    > diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
    > index b6ff4a1..26514a7 100644
    > --- a/net/ceph/messenger.c
    > +++ b/net/ceph/messenger.c
    > @@ -2131,8 +2131,8 @@ void ceph_messenger_destroy(struct ceph_messenger *msgr)
    >        dout("destroy %p\n", msgr);
    >        kunmap(msgr->zero_page);
    >        __free_page(msgr->zero_page);
    > -       kfree(msgr);
    >        dout("destroyed messenger %p\n", msgr);
    > +       kfree(msgr);
    >  }
    >  EXPORT_SYMBOL(ceph_messenger_destroy);
    >
    >
    > --
    > Jesper Juhl <jj@chaosbits.net>            http://www.chaosbits.net/
    > Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
    > Plain text mails only, please.
    >
    > --
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    >



    --
    Thanks,
    //richard
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