Re: [PATCH kselftest/test] kunit: Always print actual pointer values in asserts

[Brendan Higgins]

On Thu, Nov 21, 2019 at 3:51 PM David Gow <davidgow@xxxxxxxxxx> wrote:
>
> KUnit assertions and expectations will print the values being tested. If
> these are pointers (e.g., KUNIT_EXPECT_PTR_EQ(test, a, b)), these
> pointers are currently printed with the %pK format specifier, which -- to
> prevent information leaks which may compromise, e.g., ASLR -- are often
> either hashed or replaced with ____ptrval____ or similar, making debugging
> tests difficult.
>
> By replacing %pK with %px as Documentation/core-api/printk-formats.rst
> suggests, we disable this security feature for KUnit assertions and
> expectations, allowing the actual pointer values to be printed. Given
> that KUnit is not intended for use in production kernels, and the
> pointers are only printed on failing tests, this seems like a worthwhile
> tradeoff.

I agree. However, I also remember that others in the past yelled at me
for assuming that KUnit would not be built into production kernels.

I feel like +Kees Cook would have a good opinion on this (or will at
least CC the right people).

>
> Signed-off-by: David Gow <davidgow@xxxxxxxxxx>

Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>

Thanks!