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    SubjectRe: [Cocci] [RFC] coccicheck: add a test for repeat memory fetches
    On Wednesday 11 January 2017 05:34 AM, Kees Cook wrote:
    > On Tue, Jan 10, 2017 at 1:14 PM, Julia Lawall <> wrote:
    >> OK, I have the impression that what you are looking for is the following,
    >> that currently does not seem to work well. Still maybe it gives an idea.
    >> The basic pattern is the following sequence:
    >> 1. copy_from_user
    >> 2. test on a field of the copied value
    >> 3. another copy_from_user
    >> 4. a use of the same field as tested in step 2 from the structure obtained
    >> by the second copy_from_user or a function call with the structure as an
    >> argument
    > This looks pretty good!
    >> In the case where the second copy_from_user stores the result in a
    >> pointer, then a return with no reference of the tested field is also a
    >> concern, unless, the pointer was already kfreed.
    > I think sequence "2" above missing just looking at a direct value,
    > like if instead of a field it was a u32. Also, should binop include
    > "=="?
    > And we need to add back in get_user() too... hmmm

    May be having a separate script for get_user would be a good idea.
    get_user needs few more tests than copy_from_user. Also, for the both
    cases we can later add multi-function handling rules. And for the
    get_user, may be combinational usage rule as well.

    > -Kees

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