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    SubjectRe: truncate shows non zero data beyond the end of the inode with MAP_SHARED
    On Thu, Sep 16, 2004 at 10:49:33AM +0200, Helge Hafting wrote:
    > Could this "garbage" possibly be confidential data?

    I don't buy much in this theory.

    > I.e. one user repeatedly makes and mmaps a 1-byte file,
    > extends it to 4k, and looks at the 4095 bytes of "garbage".
    > Maybe he finds some "interesting stuff" when someone else's
    > confidential file just got dropped from pagecache
    > so he could mmap this 1-byte file?

    the old data got flushed below the i_size anyways, it sounds very
    strange that confidential data is present only over the i_size and not
    below the i_size, and if this guy has confidential data below the i_size
    then it'd better memset the whole page. And in theory nobody should touch
    the data over the i_size even if mmap allows to map it.
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