[cfe-dev] Disabling label-unioning in dataflow sanitizer?

[Christian Convey]

Sorry, that example wasn't correct.  I should have written:

int c = a + b; // c will never have a label in this case.
int d = a; // d will always get a's label

On Tue, Feb 3, 2015 at 12:09 PM, Christian Convey <
christian.convey at gmail.com> wrote:

> Hi guys,
>
> Does anyone know if clang's dataflow sanitizer supports the following
> option, or if there are plans to?
>
> Right now (clang 3.6), it seems that when two or more inputs of a given
> operation carry different labels, the resulting value is tagged with the
> *union* of those labels.  But I'm interested in a different kind of
> analysis, where I track the pristine flow of a value.  So in my analysis,
> when an operation does anything other than cleanly propagate an input value
> to its output, I want the output to be unlabeled.
>
> For example, if we have:
>    int c = a + b;
> Then I want 'c' to be have a dfas label if and only if 'a' and 'b' both
> have the same label.
>
> Thanks,
> Christian
>
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