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    SubjectRe: [PATCH] kref: Avoid null pointer dereference after WARN
    On Tue, Jun 27, 2017 at 4:49 PM, Andi Kleen <ak@linux.intel.com> wrote:
    > Is there any data how many security holes this would have
    > caught? Please no hand waving. A lot of the recent
    > security patches seem to have gone in with just a lot of
    > hand waving and security theater

    I don't practice security theater. What an offensive insinuation.
    Maybe you just meant this about other patches, however.

    The point was that if there prior was a WARN_ON, this needs to be a
    BUG_ON, since if the WARN_ON was put there with any validity,
    continuing after it will always be "fatal and potentially
    exploitable". Thus, it'd be better to change that to simply "fatal but
    not potentially exploitable". Not security theater. Logic fix.

    The bigger question, though, is the value of these checks in the first
    place. Has anybody written a coccinelle check to look into this
    statically? Has it historically been a useful thing for driver
    developers to have? Is it good defense in depth or is it overkill? At
    the very least, the original authors of kref thought a WARN_ON was
    warranted, which means probably a BUG_ON is a sensible fix, until
    somebody does the work of investigating these more careful questions.

    Jason

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