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    SubjectRe: [patch 1/2] Validate itimer timeval from userspace
    On 3/18/06, Andrew Morton <akpm@osdl.org> wrote:
    > Thomas Gleixner <tglx@linutronix.de> wrote:
    > >
    > > According to the specification the timeval must be validated and
    > > an errorcode -EINVAL returned in case the timeval is not in canonical
    > > form. Before the hrtimer merge this was silently ignored by the
    > > timeval to jiffies conversion. The validation is done inside
    > > do_setitimer so all callers are catched.
    > >
    [...]
    >
    > From my reading, 2.4's sys_setitimer() will normalise the incoming timeval
    > rather than rejecting it. And I think 2.6.13 did that too.
    >
    > It would be bad of us to change this behaviour, even if that's what the
    > spec says we should do - because we can break existing applications.
    >
    > So I think we're stuck with it - we should normalise and then accept such
    > timevals. And we should have a big comment explaining how we differ from
    > the spec, and why.
    >

    Wouldn't this only break existing applications that do incorrect
    things (passing invalid values) ?
    If that's the case I'd say breaking them is OK and we should change to
    follow the spec.

    I don't like potential userspace breakage any more than the next guy,
    but if the breakage only affects buggy applications then I think it's
    more acceptable.

    --
    Jesper Juhl <jesper.juhl@gmail.com>
    Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
    Plain text mails only, please http://www.expita.com/nomime.html
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